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THE CHEMISTRY 



.OF. 



Plant and Animal Life 



...BY.. 



HARRY SNYDER, B.S., 

Professor of Agricultural Chemistry, University of Minnesota, and 
Chemist of the Minnesota Agricultural Experiment Station. 



EASTON, PA. 
PRESS OF THE CHKMICAL PUBLISHING COMPANY. 



THE LIBRARY OF 
CONGRESS. 

Two Copies Received 

APR 4 '903 

Hjpynght Entry 
L' ■ / S~ )\ 5 
»S ^ XXft No. 

vT S S$ 

COPY B. 



Copyright, 1903, by Harry Snyder. 



tP 






PREFACE 

THIS book is the outgrowth of instruction in chem- 
istry given in the School of Agriculture of the 
University of Minnesota since 189L At first the classes 
were small and individual work with blackboard exercises 
and references to the literature in the school library was 
possible. With increased numbers of students, mimeo- 
graphed notes were supplied until finally the size of the 
classes, and the volume of the notes have necessitated 
their publication in book form. The work was first 
given, in 1 891, to a class of seven students, while twelve 
years later they numbered nearly one hundred fifty. 

The class of students to whom this instruction has 
been given have been mostly earnest workers who at- 
tended school largely from personal choice and who de- 
sired to make as much progress as possible. Numerous 
questions have been asked by them relating to the ap- 
plication of chemistry to farm and every-day life, and for 
a number of years the author kept a question box in 
which were placed the more important questions asked in 
class, and the difficulties experienced in the laboratory 
work, and in developing the work from year to year 
these questions and difficulties have been considered. 

This work was originally outlined as Agricultural 
Chemistry, but as special features have been developed 
and published, as the "Chemistry of Soils and Fertil- 
izers," and "The Chemistry of Dairying," this part of 
the subject has gradually developed into " The Chemistry 



IV PREFACE 

of Plant and Animal L,ife," and includes the composition 
of plant and animal bodies, the chemistry of the plant 
and of its food and growth, the chemistry of human 
foods and animal nutrition, the digestibility and value of 
foods and the laws governing their economic use. A few 
topics of an industrial nature but closely related to plant 
and animal life are also included. 

Before taking up the special parts relating to the chem- 
istry of plant and animal bodies, the elements and simpler 
compounds present in plants and animals, together with 
the laws governing their combinations, are considered so 
as to prepare the way for a more intelligent study of the 
subject. Laboratory practice forms an important feature, 
and questions are asked in connection with each experi- 
ment. Many of the experiments and problems are given 
to illustrate some special feature of the composition of 
plant and animal bodies. The illustrations, with the 
exception of a few as noted, are original. 

With mature earnest students, six months with a class- 
room or laboratory exercise each day are required to 
complete this work, although a longer time could ad- 
vantageously be given to the subject. It has been the 
aim throughout to present the topics in such a way that 
they would be easily understood and to develop the rea- 
soning powers of the student so that he would be able to 
make the best use of his chemistry in every-day life af- 
fairs. Harry Snyder. 

March i, 1903. 



INTRODUCTION 




LANT life and animal life are dependent upon 
the changes which are continually taking 
place in nature. The laws of nature, as far 
as they are known, are set forth in the 
various sciences among which chemistry oc- 
cupies a prominent place. In every-day life 
affairs, chemistry takes an important part because it 
is the science which treats of the composition and uses 
of substances found in nature. Plant and animal foods 
which are essential for life are simply mechanical mix- 
tures of various forms of matter which are constantly 
undergoing changes and exemplifying the laws of chem- 
istry. In agriculture, chemistry takes an important 
part, the term Agricultural Chemistry being applied to 
that branch of the science which concerns itself with the 
practical application of the laws of chemistry to the 
science of agriculture. 

In the cultivation of the soil, production of crops, feed- 
ing of animals, manufacture of farm products, prepara- 
tion and use of human foods, and in all life processes 
numerous chemical changes take place, and it is in part 
the province of chemistry to investigate these changes so 
as to assist nature in rendering the plant food of the soil 
more available, and to produce crops of the highest 
nutritive value, as well as to indicate ways in which the 
best possible use can be made of farm products in the 



VI INTRODUCTION 

feeding of animals and men. Before these subjects can 
be considered in an intelligent way, a fundamental knowl- 
edge must be obtained of some of the basic principles and 
laws of chemistry, since they are as essential to future 
work along special lines, as is a good foundation to a 
building, or a scaffold during its construction. In the 
household, arts, industries, and professions, constant 
use is made of products formed from the soil, air and 
water. In order to understand more perfectly the nature 
of the substances dealt with so as to make the most intel- 
ligent use of them., it is necessary to have a practical 
knowledge of some of the laws of chemistry and of the 
properties of the elements and compounds which enter 
into the composition of plant and animal bodies. 

To the student who begins the study of chemistry, it 
is imperative that the first part of the subject be thor- 
oughly mastered. Chemistry is different in its nature 
from many subjects. It cannot be studied in discon- 
nected parts but must be undertaken systematically. It 
cannot be absorbed by listening to lectures,, but must be 
studied. If the first part of the work is neglected, a 
failure is almost inevitable. If particular attention is 
given to the elements and their combinations, to the com- 
position of matter, to laboratory manipulations, and 
to the classification of the elements, and if the experi- 
ments are performed regularly, the student experiences a 
keen enjoyment in the subject, the work ceases to be 
drudgery and becomes a pleasure. 

The student should make an effort to learn how to 
study ; the memorizing of chemical formulas and equa- 



INTRODUCTION Vll 

ticms is not studying chemistry ; he should master the 
principles governing the combination of elements and 
then the memorizing of chemical formulas becomes un- 
necessary. In the preparation of the lessons, there are a 
number of reference books which should be consulted 
occasionally. For example, if difficulty is experienced 
with the subject of valence and radicals, the interesting 
chapter upon these topics in Ellen H. Richards' 
" Chemistry of Cooking and Cleaning" should be read. 
Remsen's "Chemistry," Hart's "Chemistry for Begin- 
ners," Storer and Lindsay's "Elementary Manual of 
Chemistry, ' ' as well as many others, will be found valuable. 
In studying the parts relating to foods, crops, and ani- 
mal feeding, Henry's "Feeds and Feeding," Jordan's 
"Feeding of Farm Animals," Armsby's "The Principles 
of Animal Nutrition," " Johnson's How Crops Grow," 
and " How Crops Feed," and the bulletins of the U. S. 
Department of Agriculture and of the several stations 
should be available. The student should early acquire the 
habit of consulting other works, as many topics are pre- 
sented more clearly in one work than in another. 

He who studies chemistry from a professional point of 
view, as medical chemistry, pharmaceutical chemistry, 
or agricultural chemistry, should remember that because 
of the limited time for the subject in professional schools, 
he is receiving at the best only a very abridged course in 
the science. Hence the necessity of supplementing the 
work by collateral reading and study ; otherwise he comes 
into contact with only one phase of the subject, and 
while he receives a technical education, he may obtain 



Vlll INTRODUCTION 

only a limited and narrow view of the science of chem- 
istry. 

In the study of the " Chemistry of Plant and Animal 
Life," it is the aim to bring the student into close contact 
with nature which is one of the requisites for perfect agri- 
culture. Although not all of the laws relating to the chem- 
istry of plant and animal life have been discovered, many 
of those relating to soils and foods, particularly human 
foods, are known and can be applied to every-day life 
affairs. 



CONTENTS 



INTRODUCTION 
Chemistry in its relation to plant and animal life ; Relation to 
other sciences ; How to study chemistry ; Reference books and how 
to use them ; Importance of chemistry. Pages v-viii. 

CHAPTER I 
Composition of Matter. — Physical and chemical changes ; Inde- 
structibility of matter ; Molecules ; Atoms ; Elements ; Com- 
pounds ; Chemical affinity ; Mechanical mixtures ; Chemical anal- 
ysis and synthesis ; Summary. Pages 1-7. 

CHAPTER II 
Properties of Elements and Compounds. — Physical properties ; 
Chemical properties ; Symbols of the elements ; Formulas of com- 
pounds ; Atomic weights ; Molecular weights ; Law of definite 
proportion ; Valence ; Combination of elements ; Problems on 
combination of elements; Experiments and questions. Pages 8-18. 

CHAPTER III 
Laboratory Manipulation. — Importance of laboratory practice ; 
Names and uses of apparatus ; Cutting glass tubing ; Bending glass 
tubing ; Perforating corks ; Weighing ; Measuring liquids ; Obtain- 
ing reagents from bottles ; Filtering ; Laboratory note-book ; 
Breakage of apparatus ; Care of sinks and plumbing ; How to ac- 
complish the best results in the laboratory. Pages 19-30. 

CHAPTER IV 
Oxygen. — Occurrence ; Preparation ; Properties ; Importance ; 
Problems, experiments, and questions ; Part taken in plant and 
animal life. Pages 31-36. 

CHAPTER V 
Hydrogen. — Occurrence ; Preparation ; Properties ; Importance ; 



X CONTENTS 

Problems, experiments, and questions ; Part taken in plant and 
animal life. Pages 37-41. 

CHAPTER VI 
Nitrogen. — Occurrence ; Preparation ; Properties ; Importance ; 
Problems, experiments, and questions ; Part taken in plant and 
animal life. Pages 42-45. 

CHAPTER VII 
Carbon.— Occurrence ; Preparation ; Properties ; Coal ; Allotro- 
pism ; A reducing agent ; Combustion ; Spontaneous Combustion ; 
A decolorizer and deodorizer ; Products of combustion ; Com- 
pounds of carbon ; Importance ; Experiments and questions ; Part 
taken in plant and animal life. Pages 4 6 ~55- 

CHAPTER VIII 
Water.— Chemical composition ; Physical properties ; Water of 
crystallization ; Natural waters ; Impurities and relation to dis- 
eases ; Location of wells ; Mineral impurities ; Contamination of 
drinking water ; Methods of improving drinking waters ; Water 
filters ; Experiments and questions. Pages 56-65. 

CHAPTER IX 
Air. — A mechanical mixture ; Carbon dioxid ; Ammonium com- 
pounds ; Moisture ; Ozone and hydrogen peroxid ; Argon and 
helium ; Organic impurities and ventilation of rooms ; Air, a source 
of plant food ; Sources of contamination of air; Experiments and 
questions; Importance of air in plant and animal life. Pages 66-71. 

CHAPTER X 
Acids, Bases, Salts and Neutralization. — Classification of ele- 
ments; Acids; Bases; Salts; Radicals; Naming of acids; Naming 
of bases ; Naming of Salts ; Double salts ; Acid salts ; Basicity of 
acids ; Two series of salts. Pages 72-79. 

CHAPTER XI 
Hydrochloric Acid, Chlorin and Chlorids. — Occurrence ; Prepara- 
tion ; Properties ; Preparation of chlorin ; Properties ; The chlorin 



CONTENTS XI 

group of elements ; Chlorids ; Problems ; Experiments and ques- 
tions. Pages 80-85. 

CHAPTER XII 
Nitric Acid and Nitrogen Compounds. — Occurrence ; Preparation ; 
Properties ; Importance ; Ammonia ; Occurrence ; Preparation ; 
Properties ; Uses ; Oxids of nitrogen ; Anhydrids ; Law of multiple 
proportion ; Importance of the nitrogen compounds ; Problems ; 
Experiments and questions. Pages 86-92. 

CHAPTER XIII 
Phosphorus and Its Compounds.— Occurrence ; Preparation ; 
Properties ; Oxids ; Phosphoric acid and phosphates ; Compounds 
of phosphorus; Importance of phosphorus and its compounds; 
Problems ; Experiments and questions. Pages 93-96. 

CHAPTER XIV 
Sulfur and Its Compounds. — Occurrence ; Preparation ; Proper- 
ties ; Uses ; Sulfur dioxid ; Sulfuric acid ; Properties of H 2 S0 4 ; 
Sulfates ; Sulfids ; Problems ; Experiments and questions. Pages 
97-102. 

CHAPTER XV 
Silicon and Its Compounds. — Occurrence ; Preparation and proper- 
ties ; Silicic acid ; Dialysis ; Silicates ; Importance of compounds of 
silicon ; Problems; Experiments and questions. Pages 103-106. 

CHAPTER XVI 
Oxids of Carbon, Carbonates, and Carbon Compounds. — Carbon 
dioxid ; Carbon monoxid ; Marsh gas ; Hydrocarbons ; Petroleum ; 
Use of gasoline ; Illuminating gas ; Mineral oils ; Oil of turpentine ; 
Creosote ; Benzene or benzol ; Aliphatic and aromatic series of com- 
pounds ; Carbon disulfid ; Cyanids ; Carbids ; Fuels ; Caloric value 
of fuels ; Foods ; Production of organic compounds in plants ; De- 
cay of organic compounds; Experiments. Pages 107-119. 

CHAPTER XVII 
Writing Equations. — Importance ; Common errors in writing 



xil CONTENTS 

equations ; Impossible reactions ; A knowledge of reacting com- 
pounds and products necessary ; Equations for class room work. 
Pages 120-126. 

CHAPTER XVIII 
Potassium, Sodium, and Their Compounds. — Occurrence of potas- 
sium ; Potassium hydroxid ; Potassium nitrate ; Potassium car- 
bonate ; Potassium chlorate : Potassium sulfate ; Miscellaneous 
potassium salts ; Occurrence of sodium ; Sodium chlorid ; Sodium 
nitrate ; Sodium carbonate ; Sodium hydroxid ; Sodium phosphate ; 
Miscellaneous sodium salts ; Experiments. Pages 127-133. 

CHAPTER XIX 

Calcium, Magnesium, and Their Compounds. — Occurrence of cal- 
cium ; Calcium carbonate ; Calcium oxid ; Calcium hydroxid ; Cal- 
cium sulfate ; Calcium chlorid ; Bleaching-powder ; Calcium phos- 
phate ; Mortar ; Glass ; Occurrence of magnesia ; Magnesium salts ; 
Experiments. Pages 134-139. 

CHAPTER XX 

Iron, Aluminum, and Their Compounds. — Occurrence of iron ; 
Reduction of iron ores ; Wrought iron ; Steel ; Rusting of iron ; 
Iron compounds ; Occurrence of aluminum ; Alums ; Pottery ; Ex- 
periments. Pages 140-147. 

CHAPTER XXI 

Copper, Zinc, Lead, Tin, Arsenic, Mercury, Their Compounds and 
Alloys.— Commercial importance ; Occurrence of copper and its 
metallurgy ; Copper sulfate ; Bordeaux mixture ; Occurrence of 
zinc ; Compounds of zinc ; Galvanized iron ; Occurrence of tin ; Tin 
salts ; Occurrence of lead ; Oxids of lead ; Lead carbonates ; Lead 
salts ; Uses of lead ; Occurrence of arsenic ; Paris green ; Occur- 
rence of mercury ; Compounds of mercury ; Experiments. Pages 

I48-I54- 

CHAPTER XXII 

The Water-Content and Ash of Plants. — Water; Dry matter; 
Plant ash ; Form of the ash elements ; Amount of ash in plants ; 
Importance of ash elements ; Water culture ; Sand culture ; Occur- 
rence and function of ash elements ; Potassium ; Sodium ; Calcium : 



CONTENTS Xlll 

Magnesium ; Aluminum ; Iron ; Phosphorus ; Sulfur ; Silicon ; Chlo- 
rin ; Experiments ; Problems. Pages 155-174. 

CHAPTER XXIII 
The Non-Nitrogenous Organic Compounds of Plants. — Organic 
matter ; Non-nitrogenous and nitrogenous organic compounds ; 
Classification of non-nitrogenous compounds ; Carbohydrates ; 
General characteristics ; Cellulose ; Occurrence ; Physical proper- 
ties ; Chemical properties ; Function and value ; Food value ; 
Amount of cellulose in plants ; Crude fiber ; Starch ; Occurrence ; 
Physical properties ; Chemical properties ; Function and value ; 
Foo value of starch ; Amount of starch in plants ; Dextrin ; Struc- 
tural formulas ; Sugar ; Classification of sugars ; Occurrence of 
sucrose ; Physical and chemical properties of sucrose ; Milk-sugar ; 
Maltose; Inversion of sucrose; Refining of sugar ; Occurrence of 
dextrose ; Chemical and physical properties ; Levulose ; Miscel- 
laneous sugars ; Optical properties of sugar ; Sugar-beets ; Food 
value of sugar ; Gums ; Pentosans ; Pectin bodies ; Nitrogen-free 
extract ; Fats ; Presence in plants ; Physical properties ; Chemical 
composition ; Stearin ; Palmitin ; Olein ; Miscellaneous fats ; Saponi- 
fication ; Fatty acids ; Waxes ; Food value of fat ; Amount of fat 
in plants and foods ; Ether extract ; Organic acids ; Occurrence in 
plants ; Tartaric acid ; Malic acid ; Succinic acid ; Oxalic acid ; 
Citric acid ; Tannic acid ; Function and food value of the organic 
acids ; Essential oils ; General properties ; Occurrence ; Chemical 
composition and properties ; Essential oils of agricultural crops ; 
Synthetic production of essential oils ; Amount of essential oils in 
plants ; Food value ; Miscellaneous compounds in plants ; Relation- 
ship of non-nitrogenous compounds of plants ; Food value of the 
non -nitrogenous compounds ; Experiments and questions. Pages 

I75-2I3- 

CHAPTER XXIV 

The Nitrogenous Organic Compounds of Plants.— Amount of 
nitrogenous matter in plants ; Different terms applied to nitroge- 
nous compounds; Complexity of composition; Classification of 
nitrogenous compounds ; Proteids ; General composition ; Oc- 
currence ; Physical properties ; Chemical properties ; Classification 



XIV CONTENTS 

of proteids ; Albumins ; Globulins ; Albuminates ; Peptones and 
proteoses ; Insoluble proteids ; Food value of proteids ; Amount in 
plants ; Crude protein ; Albuminoids ; Composition ; Nuclein ; 
Gelatin ; Mucin ; Elastin ; Food value of albuminoids ; Amides and 
amines ; Composition and properties ; Formation and Occurrence 
in plants ; Formation and occurrence of amides in animals ; Food 
value ; Amount in foods ; Protein production and disintegration ; 
Alkaloids ; General composition ; Plant alkaloids ; Animal alka- 
loids ; Food value and production ; Mixed nitrogenous com- 
pounds ; Lecithin ; Nitrogenous glucosides ; General relationship 
of the nitrogenous organic compounds of foods ; Problems and ex- 
periments. Pages 214-234. 

CHAPTER XXV 

Chemistry of Plant Growth. — Seeds ; Ash ; Non-nitrogenous com- 
pounds; Nitrogenous compounds; Chemical changes during germi- 
nation ; Change of starch to soluble forms ; Change of fats to 
starch ; Change of insoluble proteids to soluble forms ; Germina- 
tion of seeds and digestion of food compared ; Necessary condi- 
tions for germination ; Heavy- and light-weight seeds ; Movement 
of plant juices ; Joint action of chemical and physical agents; Poro- 
sity of tissues ; Osmosis ; Chlorophyl and protoplasm ; Chemical 
action in leaves of plants ; Production of chlorophyl ; Function ; 
Production of organic matter ; Experiments. Pages 235-246. 
CHAPTER XXVI 

Composition of Plants at Different Stages of Growth.— Composi- 
tion and stage of growth ; Assimilation of mineral food by the 
wheat plant ; Assimilation of nitrogen by the wheat plant ; Clover ; 
Rapidity of growth; Flax; Rapidity of growth; Maize (corn) ; 
Importance ; Roots ; Stalks ; Leaves ; Tassel ; Husks ; Ripening 
period. Pages 247-256. 

CHAPTER XXVII 
Factors which Influence the Composition and Feeding Value of 
Crops.— Seed ; Soil ; Climate ; Stage of maturity ; Method of 
preparation as food ; Improving the feeding value of forage crops. 
Pages 257-262. 



CONTENTS XV 

CHAPTER XXVIII 
Composition of Coarse Fodders.— Coarse fodders; Straw; Tim- 
othy hay , Hay, similar to timothy ; Oat hay ; Hay, similar to oat 
hay ; Bromus inermis ; Clover hay ; Alfalfa and fodders similar to 
clover ; Rape ; Pasture grass ; Corn fodder and stover ; Silage. 
Pages 263-272. 

CHAPTER XXIX 
Wheat. — Structure of kernel ; Proteids of wheat ; Relation of 
nitrogen in wheat to nitrogen content of flour ; Influence of ferti- 
lizers upon composition of wheat ; Variations in composition of 
wheat ; Storage in elevators ; Grading ; Composition of Unsound 
wheat ; Composition of different varieties ; American and foreign 
wheats ; Wheat as animal food ; As human food ; Experiments and 
questions. Pages 273-288. 

CHAPTER XXX 
Maize (Indian Corn). — Structure of the kernel; Composition; 
Proteids ; Nitrogenous and non-nitrogenous corn ; Varieties ; 
Grading ; Corn products ; Corn as a food ; Experiments. Pages 
289-295. 

CHAPTER XXXI 

Oats, Barley, Rye, Buckwheat, Rice, and Miscellaneous Seeds. — 
Structure of the oat kernel ; Composition of oats ; Oats as human 
and animal foods ; Barley ; Rye ; Rice ; Buckwheat ; Millet seed ; 
Peas and beans ; Grading of grains ; Experiments. Pages 296-302. 

CHAPTER XXXII 
Mill and By-Products. — Sources ; Wheat by-products ; Wheat 
bran ; Wheat shorts ; Wheat germ ; Wheat screenings ; Linseed 
meal ; Cottonseed cake and meal ; Oat feed ; Gluten meal ; Malt 
sprouts ; Miscellaneous by-products ; Inspection of feeding stuffs ; 
Problems and experiments. Pages 303-311. 

CHAPTER XXXIII 
Roots, Tubers and Fruits. — General composition ; Potatoes; Car- 
rots ; Parsnips ; Mangel wurzels ; Apples ; Oranges ; Lemons ; Straw- 
berries ; Grapes ; Olives ; Dried fruits ; Miscellaneous fruits ; Food 
value. Pages 312-317. 



XVI CONTENTS 

CHAPTER XXXIV 
Fermentation. — Insoluble ferments ; Soluble ferments or enzymes ; 
Aerobic and anaerobic ferments ; Conditions necessary for fermen- 
tation ; Soil ferments ; Ferments in seeds ; Ferments in bread- 
making ; Ferment action and food digestion ; Ferments and food 
preservation ; Ferments in butter- and cheese-making ; Disease- 
producing organisms ; Beneficial organisms ; Experiments. Pages 
318-324. 

CHAPTER XXXV 
Chemistry of Digestion and Nutrition. — Digestion, a bio-chemical 
process ; Digestion experiments ; Caloric value of foods ; Available 
energy of foods ; Net energy of foods ; Digestion of proteids ; Di- 
gestion of the carbohydrates ; Digestion of fats ; Oxygen necessary 
for digestion ; Factors influencing digestion ; Mechanical con- 
dition ; Combination of foods ; Amount of food consumed ; Pala- 
tability ; Individuality ; Miscellaneous factors influencing digesti- 
bility ; Application of digestion coefficients ; Digestible nutrients 
of foods ; Problems. Pages 325-342. 

CHAPTER XXXVI 
Rational Feeding of Animals. —Balanced rations ; A maintenance 
ration ; Standard rations ; Food requirements of animals ; Food 
supply at different stages of growth ; Food requirements of horses ; 
Selection of food for horses ; Foods required for beef production ; 
Selection of foods for beef production ; Food requirements of dairy 
cows; Selection of foods for dairy cows; Food requirements of 
swine ; Food requirements of sheep ; Calculation of balanced 
rations ; Nutritive ratio ; Comparative cost and value ; Caloric value 
of rations ; Sanitary conditions ; Problems. Pages 344-365. 

CHAPTER XXXVII 
Composition of Animal Bodies. — Water and dry matter ; Mineral 
matter ; Fat ; Nitrogenous matter ; Proteids of meat ; Albumin ; 
Myosin ; Syntonin ; Hemoglobin ; Insoluble Proteids ; Peptones'; 
Keratin ; Albuminoids ; Gelatin ; Influence of food upon the com- 
position of animal bodies ; Composition of human body. Pages 
366-373- 



CONTENTS XV11 

CHAPTER XXXVIII 
Rational Feeding of Men. — Similarity of the principles of human 
and animal feeding ; Dietary standards ; Amount of food con- 
sumed per day ; Calculating a balanced ration ; Comparative cost 
and value of foods ; Factors influencing digestibility ; Requisites of 
a ration ; Dietary studies ; Chemical changes in the cooking of 
foods ; Refuse and waste matters ; Doss of nutrients in the 
preparation of foods ; Mineral matter in a ration ; Digestibility of 
foods ; Digestibility of animal foods ; Digestibility of vegetable 
foods ; Relation of food to health ; Tables of composition of human 
foods. Pages 374-398. 



CHAPTER I 
Composition of Matter 

i. Physical and Chemical Changes. — All substances 
in nature are subject to change in form and composition. 
At a low temperature, water is converted into ice, and by 
the application of heat into steam. The three forms 
which water may assume— solid, liquid, and vapor — are 
simply different conditions in which it is capable of ex- 
isting. When water is changed into steam or ice, noth- 
ing is either added to or taken from the particles of water, 
simply a change of form or a physical change takes place. 
When, however, an electric current is passed through 
water, the water is decomposed and two gases are pro- 
duced. When such a change takes place, the water par- 
ticles are subjected to a change in composition called a 
chemical change. 

Limestone may be pulverized until it is as fine as wheat 
flour, and when examined w 7 ith a microscope, each frag- 
ment is in all respects like the original piece, except in 
size. The crushing has resulted in simply dividing the 
limestone into a large number of particles. If, however, 
a piece of limestone is burned in a lime kiln, the product 
is entirely different in its properties from the original 
lime rock. When water is added to burned lime, it 
slakes, heat is generated, and steam is given off, while, 
when water is added to lime rock, no appreciable change 
takes place. 

Changes which affect the form but not the composition 
of matter are known as physical changes. The produc- 
tion of steam from water, the freezing of water, the pul- 



2 AGRICULTURAL CHEMISTRY 

verizing of limestone, and similar changes which do not 
affect the composition of the material, are physical 
changes. When milk sours, fruits decay, or wood is 
burned, a different kind of change takes place. The 
smallest particles of which each of the materials is com- 
posed undergo a change in composition. The products 
formed are entirely different in character from the origi- 
nal substances. Such changes, which affect the identity 
or individuality of a material, are chemical changes. 

2. Physics is the science which concerns itself with the 
changes which matter undergoes when the ultimate par- 
ticles of a material retain their identity or individuality. 

Animal and plant life are to a great extent dependent 
upon the physical changes which take place in the soil. 
Rain is the result of the action of physical agencies, as is 
also the pulverization of rocks and soils. In all manu- 
facturing operations, and as the result of all kinds of 
manual labor, particularly upon the farm and in the 
workshop, physical changes are continually taking place. 

3. Chemistry is the science which deals with the 
changes which matter undergoes when the ultimate par- 
ticles lose their identity or individuality, and the prod- 
ucts formed are entirely different from the original mate- 
rial. 

Chemical changes are continually taking place. 
Plant growth and animal life are dependent largely upon 
the chemical as well as the physical changes which take 
place in the soil and in the air. Life processes are inti- 
mately associated with chemical changes. Chemical and 
physical changes are closely related ; a chemical change 



COMPOSITION OF' MATTER 3 

is often dependent upon a physical change, and a physi- 
cal change is, in turn, often dependent upon a chemical 
change. A chemical change necessarily brings about a 
physical change. While the sciences of chemistry and 
physics are, to a certain extent, closely related, each 
nevertheless deals with a different phase of change which 
matter undergoes. 

4. Indestructibility of Matter. — When either a chem- 
ical or physical change takes place, no matter is destroyed 
or produced. It is not possible either to create or destroy 
matter. This is known as the law of indestructibility oj 
77iatter. 

Whenever a chemical change takes place, the parts 
which make up the substance are rearranged in a new and 
different way, or they are combined with other materials. 
When wood is burned, it is changed into gaseous prod- 
ucts and ashes ; the materials which composed the wood 
are not lost to nature, they simply assume a different 
form. The law of indestructibility of matter is one of the 
foundation principles of chemistry. It was believed, at 
one time, that metals, as copper, could be changed into 
gold, and other substances into different forms of matter. 
After many centuries of experimenting, it was found 
that this could not be done, and as the result, the law of 
indestructibility of matter was established. 

5. riolecules. — It is possible, by mechanical means, as 
pulverizing, to reduce substances to a very fine state of 
division, and it is believed that if this division could be 
carried on by more refined methods, particles of mat- 
ter could finally be obtained that would not be suscepti- 



4 AGRICULTURAL CHEMISTRY 

ble to farther division by purely physical methods. The 
smallest particle of a material that can exist and have all 
of the properties of the original material is called a mole- 
cule. Molecules, however, have never been separated as 
individuals. All forms of matter are composed of mole- 
cules. The proof that matter is composed of molecules 
is founded upon the laws of physics. The reasons for 
the acceptance of the molecular structure of matter can- 
not be profitably undertaken by the student of elemen- 
tary chemistry, but properly form a very important part 
of advanced chemistry. The molecular structure of 
matter has been sufficiently well established to warrant 
the use of the term molecule by the student of elemen- 
tary chemistry. 

6. Atoms. — Whenever a chemical change takes place, 
the molecule is changed in composition. When an elec- 
tric current is passed through water, the molecules of 
water are split up into simpler forms of matter. It is 
evident that the molecule is not the simplest form of mat- 
ter, and that while the molecule is the smallest part of a 
substance, it is, in turn, made up of still smaller parts. 
These parts of matter which make up a molecule are called 
atoms. An atom is the smallest part of an elementary 
substance that can enter into combination to form a 
molecule. Atoms never exist in nature in a free or un- 
combined state, but unite to form molecules, and mole- 
cules in turn unite to form masses. 

7. Elements. — The simplest forms of matter, as iron,' 
copper and sulfur, from which it is impossible to extract 
or obtain simpler bodies, are called elements. The ele- 



COMPOSITION OF MATTER 5 

ment is the simplest form in which matter can exist. 
All substances found in nature, as plant and animal bod- 
ies, rocks and soils, are composed of compounds which, 
in turn, are composed of elements. There are about 74 
of these elementary forms of matter, although only about 
18 take any important part directly or indirectly, as far 
as is known, in either plant or animal life processes. 
There are a few substances found in nature in elementary 
form, as iron, copper, gold, and sulfur, but most of the 
elements are in combination with others, forming com- 
pounds. 

8. Compounds. — The substances found most abun- 
dantly in nature are compounds. A compound is formed 
by the chemical union of two or more elements. All 
compounds are made up of a definite amount, by weight, 
of separate elements which unite according to the laws of 
chemical combination. Water, for example, is a com- 
pound made up of two elements, hydrogen and oxygen. 
Sugar is a compound made up of three elements, hydrogen, 
carbon, and oxygen. When elements unite to form a 
compound, the elements lose their identity and the com- 
pound that is produced has entirely different and distinct 
chemical and physical properties from those of the ele- 
ments of which it is composed. 

9. Chemical Affinity. — The force or power which 
causes elements to combine to form compounds is called 
chemical affinity, and about this comparatively little is 
known. Whenever a compound is separated into its ele- 
ments, chemical affinity or the force which holds the ele- 
ments together is overcome. When elements com- 



6 AGRICULTURAL CHEMISTRY 

bine to form compounds, it is because of the chemical 
affinity which the elements have for one another. Some 
elements have a stronger affinity for certain elements than 
for others. 

10. Mechanical Mixtures. — When two or more sub- 
stances mix, but fail to unite chemically, a mechanical 
mixture is obtained. When iron and sulfur are mixed, 
a mechanical mixture is the result, and the iron and the 
sulfur can, by purely physical methods, be separated. 
If, however, a mixture of iron and sulfur is heated, a 
chemical change takes place and it is impossible by physi- 
cal methods, as by the use of a magnet or by solvents, to 
separate the iron from the sulfur. Compounds as well 
as elements may form mechanical mixtures. 

ii. Chemical Analysis and Synthesis. — Whenever a 
substance or a compound is separated into simpler com- 
pounds or elements, the process is called chemical analy- 
sis. When only the kinds of elements or simpler com- 
pounds are determined, the process is called qualitative 
analysis. If the percentage amounts are determined, it 
is called quantitative analysis. When elements or simpler 
compounds are united, the process is called synthesis. 
Synthesis and analysis are directly opposite processes. 
When substances are produced in the laboratory from 
simpler elements or compounds, it is called a synthetical 
process. Many useful compounds are produced syntheti- 
cally. 

12. Summary. — Substances may undergo either phys- 
ical or chemical changes. A physical change does not 



COMPOSITION OF MATTER 7 

destroy the identity or change the composition of the 
molecule. When a chemical change occurs, the atoms 
are combined in a different way and a new molecule is 
produced. The molecule is the smallest particle of mat- 
ter that can exist and retain its identity or individuality. 
Physics and chemistry are closely related sciences, but 
each deals with a different kind of change. Compounds 
are composed of molecules, and molecules of atoms. 
Atoms never exist free, but unite to form molecules. If 
a substance contains in its molecule only atoms of one 
kind, it is an element. If there are present atoms of 
more than one kind, it is a compound. Life processes 
are dependent largely upon the physical and chemical 
changes continually taking place in nature. 



CHAPTER II 
Properties of Elements and Compounds 
13. Physical Properties. — In order to determine the 
value of any element or compound, a knowledge of its 
chemical and physical properties is necessary, and it is 
important that a clear idea be obtained as to what is 
meant by the terms chemical and physical properties of 
elements and compounds. Each element and compound 
has its own characteristic properties, which are different 
in a number of wa}^s from those of other elements and 
compounds. The physical properties of a substance in- 
clude : 

1. Form or state of the material, as solid, liquid, or 
gas, which depends upon the temperature to which the 
substance is subjected. Many substances which are solid 
under ordinary conditions are, at higher temperatures, 
converted into liquids or vapors ; and substances which 
are gases are in turn converted into liquids and solids at 
low temperature and under high pressure. 

2. Weight or specific gravity. The weight or specific 
gravity of a material depends upon its molecular struc- 
ture and upon the character of its individual molecules. 
Some of the elements and compounds have molecules of 
greater weight than have others. Liquids and gases are 
characterized as light or heavy according to their weight, , 
compared with some material taken as the standard. 

3. Color. The color of a compound is a physical prop- 
erty which is due to its chemical composition. Many of 



ELEMENTS AND COMPOUNDS 9 

the elements, as copper, silver, and gold, have character- 
istic colors. Some compounds owe their value entirely to 
their color, and are used for paints and dyes. 

4. Odor and taste. The odor and taste of an element 
or compound are physical properties which are character- 
istic of the element or compound. 

5. Electrical characteristics. Elements and compounds 
have definite electrical properties. They are either good 
or poor conductors of electricity, and offer a large or small 
amount of resistance to the passing of an electric current. 

The way in which a substance responds to pressure, 
water, heat, and cold, depends upon its physical proper- 
ties, and the physical properties in turn are modified by 
these agencies. 

In the study of the elements and their compounds, the 
physical properties are also included because our knowl- 
edge of chemistry would be incomplete without consider- 
ing the physical as well as the chemical properties of 
substances. 

14. Chemical Properties.— In addition to the physical 
properties, each element and compound has definite chem- 
ical properties. This is because the molecules of the 
different elements are unlike in character and some of the 
elements and compounds are more readily affected by 
chemical agencies than are others. The molecules of 
compounds are made up of atoms of different kinds which 
impart different properties to the molecule. Copper, for 
example, has different chemical properties from gold. It 
will dissolve more readily in acids, tarnish in the air, and 
be acted upon more rapidly by other bodies than will 



IO AGRICULTURAL CHEMISTRY 

gold. When iron is exposed to moisture and air it rusts, 
while aluminum is not readily affected by these agents. 
This is because iron and aluminum have different chem- 
ical properties. The chemical properties of a substance 
include the way in which it combines or produces chem- 
ical change when brought into contact with other ele- 
ments or compounds. Some elements are characterized 
as chemically active or inactive. An active element is 
one that readily unites or combines with other elements, 
while an inactive or passive element is one that does not 
readily unite or combine. Some elements are active 
under certain conditions and with some of the elements, 
and inactive under other conditions and with other ele- 
ments. The various elements require different conditions 
for producing chemical changes. In studying an element, 
the way in which it deports itself in producing chemical 
changes, the ability with which it combines with other 
elements, and the products which are formed as the re- 
sult of the chemical changes, are some of the more impor- 
tant chemical properties considered. 

The study of the chemical and physical properties of 
elements and their compounds is important in many ways, 
as the value of a substance depends entirely upon its 
properties. In the growing and cultivation of crops, the 
production, preparation, and the economic use of foods, 
the treatment of diseases, and in all manufacturing opera- 
tions, as the smelting and refining of metals, the chemical 
and physical properties of the elements and their com- 
pounds are constantly made use of. 

15. Symbols of the Elements. — In the study of chem- 



ELEMENTS AND COMPOUNDS 



II 



istry, a characteristic system of notation is used. The 
name of an element, as oxygen, is not written in full, but 
a symbol or sign, denoting the element is employed. In 
the case of oxygen, the symbol is O. The symbol of an 
element is either the first letter of the name of the ele- 
ment, or the first with some characteristic letter, as CI 
for chlorin. In some cases, the symbols are derived 
from the Latin names of the elements, as Fe (Ferrum) 
for iron. By use, the student soon becomes familiar with 
those symbols most commonly used. 



Name. Symbo 

Aluminum Al 

Antimony Sb 

Arsenic As 

Barium Ba 

Bismuth Bi 

Boron B 

Bromin Br 

Calcium Ca 

Carbon C 

Chlorin CI 

Chromium .... Cr 

Cobalt Co 

Copper Cu 

Fluorin F 

Gold Au 

Hydrogen H 

Iodin I 

Iron Fe 

Lead Pb 

Lithium Li 

Magnesium Mg 

Manganese Mn 

Mercury Hg 



iproximate 


Va- 


Kind of 


tnic weight. 


lence. 


element. 


27 


3 


Base-forming 


120.5 


3, 5 




75 


3. 5 




137-5 


2 


Base-forming 


208 


3, 5 




11 


3 


Acid-forming 


80 


1 


Acid-forming 


40 


2 


Base-forming 


12 


2, 4 


Acid-forming 


35-5 


1 


Acid-forming 


52 


4,6 




59 


2, 4 


Base-forming 


64 


1, 2 


Base-forming 


19 


1 


Acid-forming 


197 


3 


Base-forming 


127 


1 


Acid-forming 


56 


2, 3, 4 


Base-forming 


207 


2, 4 


Base-forming 


7 


1 


Base-forming 


24 


2 


Base-forming 


55 


2, 4, 6 




200 


1, 2 


Base-forming 



12 AGRICULTURAL CHEMISTRY 

Approximate Va- Kind of 

Name. Symbol, atomic weight, lence. element. 

Nickel Ni 59 2,4 Base-forming 

Nitrogen N 14 3, 5 Acid-forming 

Oxygen 16 2 Acid-forming 

Phosphorus P 31 3,5 Acid-forming 

Platinum Pt 195 4 Base-forming 

Potassium K 39 1 Base-forming 

Silicon Si 28 4 Acid-forming 

Silver Ag 10S 1 Base-forming 

Sodium Na 23 1 Base-forming 

Sulfur S 32 2,4 Acid-forming 

Tin Sn 119 2,4 Base-forming 

Zinc Zn 65.5 2 Base-forming 

16. Formulas of Compounds. — Since compounds are 
composed of elements, it is possible, by means of combi- 
nation of symbols, to express the formula of a compound. 
The formula of a compound denotes the number and 
kinds of elements contained ; as, for water, the formula 
H 2 designates that the compound is composed of the 
two elements hydrogen and oxygen ; and for sugar, the 
formula C 12 H 22 O n denotes that the compound is made up 
of three elements, carbon, hydrogen, and oxygen. The 
formula always expresses the composition. In the for- 
mulas of compounds, figures are made use of, as 2 in H 2 0, 
at the right of the H and partially below the line. In 
this formula, the 2 indicates that there are two atoms of 
H in the molecule. In the case of sugar, the figures used 
mean that in one molecule of sugar there are 12 atoms of 
C, 22 atoms of H, and 11 of O. The formula of a com- 
pound always represents one molecule of the compound 
unless some figure is placed to the left of the formula, as 
2H 3 0. When placed in this position, the 2 designates 



ELEMENTS AND COMPOUNDS 1 3 

that there are two molecules of water. Figures placed to 
the left of a formula and on the same line indicate the 
number of molecules, while figures to the right of the in- 
dividual element represent the number of atoms of ele- 
ments in each molecule. Hence the formula of a com- 
pound always designates the composition of the molecule, 
and the number and kind of atoms contained. Farther 
study of the formulas of compounds will show that addi- 
tional facts, as composition by weight and volume, are 
also represented. 

Exercise. — Name the elements, the number of molecules, and 
the number of atoms in each molecule in the following formulas : 
NaCl, CaClj, 2KCI, 2K 2 S0 4 , Al 2 O s , 5N 2 5 , H 2 SO i( NaOH, HP0 3 . 

17. Atomic Weights. — An atom is the smallest part of 
an element present in a molecule. Atoms have definite 
properties, as weight. Hydrogen is the lightest material 
known. An atom of hydrogen, or the smallest part of 
hydrogen which can enter into chemical combination, is 
considered as having a weight of 1. The weight of the 
atom of any element is the number of times heavier that 
atom is than hydrogen, which is the standard. Oxygen, 
for example, has an atomic weight of 16, that is, an atom 
of oxygen weighs 16 times as much as an atom of hydro- 
gen. Carbon has an atomic weight of 12, that is, an 
atom of carbon is 12 times as heavy as an atom of hydro- 
gen. The way in which the atomic weights are obtained 
cannot, at this stage of the work, be profitably considered. 
Atomic weights are, however, obtained with a high de- 
gree of accuracy, and while the individual atoms and 
molecules are not susceptible, at the present time, to sep- 



14 AGRICULTURAL CHEMISTRY 

aration and weighing, the comparative weight, or the 
number of times heavier or lighter a definite number of 
molecules is than a similar number of molecules, in other 
forms of matter, can be accurately determined. While 
the absolute weight of a molecule or atom cannot be 
determined, its comparative weight can be. When chlo- 
rin, for example, combines with hydrogen, it is known 
that 35.45 times as much, by weight, of chlorin as of 
hydrogen has entered into combination. Hence the 
smallest part by weight of chlorin which can combine, 
must weigh at least 35.45 times as much as the weight of 
the smallest particle of hydrogen which enters into com- 
bination. The atomic weights of the more common ele- 
ments are given in the table on page 1 1 . 

18. Molecular Weights.— Since the molecules of com- 
pounds are composed of a definite number of atoms of 
elements, and each atom has a definite weight, it neces- 
sarily follows that a molecule has a definite weight. In 
the case of water, the formula H 2 represents one mole- 
cule of water, composed of two atoms of hydrogen and 
one of oxygen. As the atoms have definite weights, the 
weight of the molecule H 2 is the sum of the weights of 
the atoms in the molecule. Since hydrogen is taken as 
the standard and weighs 1 , and there are two atoms of 
hydrogen, and one atom of oxygen weighing 16, the 
weight of the molecule will be 2 + 16 or 18 ; that is, the 
molecule of water, H 2 0, is 18 times heavier than one 
atom of hydrogen. 

Exercise. — Compute the molecular weights of the compounds 
given in the exercise following the formulas of the compounds, 
Section 16. 



ELEMENTS AND COMPOUNDS 15 

19. Law of Definite Proportion. — A study of the com- 
bination of elements has shown that always when elements 
unite to form compounds, a definite weight of each ele- 
ment enters into the composition. This is known as the 
law of definite proportion. Chemical combination always 
takes place between definite weights of the elements, and 
a chemical compound always contains the same elements 
in exactly the same proportion by weight. The law of 
definite proportion is one of the foundation principles of 
modern chemistry, and has enabled the chemist to deter- 
mine the composition of bodies. This law is founded 
upon facts independent of any hypothesis, and the accu- 
racy of the law has been demonstrated by many investi- 
gators. 

The theories relating to the composition of matter, par- 
ticularly to atoms and molecules, are in harmony with 
this law of definite proportion. It is believed, since 
chemical combination takes place between definite masses 
of elements, it must also take place between the smallest 
particles of the substances. Since the smallest particles 
which enter into chemical composition are the atoms, 
chemical combination must take place between the atoms. 
The atoms all possess definite weights. Hence it can 
readily be understood why chemical combination takes 
place between definite weights of the elements. The 
next step in the study of the composition of matter is the 
way in which the elements combine, or the power of com- 
bination ; this is known as valence. 

20. Valence. — The valence of elements is the power 
which an atom of one element has of holding in chem- 



1 6 AGRICULTURAL CHEMISTRY 

ical combination a definite number of atoms of other ele- 
ments. Carbon, for example, has the power of uniting 
with or holding in chemical combination four hydrogen 
atoms ; carbon is said, therefore, to have a valence of 4. 
Elements which have power to hold only one atom of hy- 
drogen in combination are called monovalent. Hydro- 
gen is a monovalent element. Bivalent, trivalent, tetra- 
valent, and pentavalent elements are those whose atoms 
have the power of uniting with 2, 3, 4, and 5 atoms 
of hydrogen or other monovalent elements. The valence 
of an element is spoken of as its combining power. Some 
of the elements have more than one valence. The va- 
lences of some of the more common elements are given 
on page 1 1 . 

21. Combination of Elements. — The combination of 
two elements to form compounds is always governed by 
the valence of the elements. When calcium and chlorin 
combine, the combination takes place in a definite way ;". 
calcium has a valence of 2 ; chlorin has a valence of 1 ;. 
hence, in order to make a chemical combination, it will 
take one atom of Ca, having a valence of 2, to combine 
with two atoms of CI, each CI atom having a valence of 
1. CaCl 2 is the formula. Calcium could not combine 
with three atoms of chlorin, because compounds com- 
posed of two elements are always formed according to the 
valence of the elements. The valence of calcium, 2, lim- 
its the number of atoms of chlorin with which it can com- 
bine. If one of the elements, as oxygen, has a valence 
of 2, and the other element, as carbon, has a valence of 
4, 2 atoms of oxygen, each atom having a valence of 2, 



ELEMENTS AND COMPOUNDS 1 7 

will be required to combine with i atom of carbon, hav- 
ing a valence of 4. The formula is C0 2 . In the for- 
mulas of compounds, the valences of the atoms uniting 
are always balanced or satisfied. 

When two elements combine, and one of them has an 
odd valence, as phosphorus, which has a valence of 3, 
two atoms of the element with the odd valence are always 
required for combination. For example, two phosphorus 
atoms, each having a valence of 3, making a total valence 
of 6, require, in order to combine with O, whose valence 
is 2, three atoms of O, which make the valence of 6. The 
two atoms of phosphorus combine with the three atoms 
of oxygen, making a balanced compound, and the va- 
lences of the phosphorus and oxygen are satisfied. The 
compound is P 2 3 . 

Combine according to the lowest valence, the following 
elements, and give the formulas of the compounds pro- 
duced. 

Zinc and oxygen Sulfur and oxygen 

Calcium and oxygen Sodium and chlorin 

Tin and oxygen Potassium and chlorin 

Iron and oxygen Carbon and oxygen 

Potassium and oxygen Phosphorus and oxygen 

Silicon and oxygen Iron and sulfur 

Potassium and sulfur 
Manganese and sulfur 
Phosphorus and hydrogen 
Calcium and chlorin 
Aluminum and oxygen 
Phosphorus and oxygen 
Problem 1. — How much hydrogen is required to combine with 20 
grams of O to form H 2 ? When hydrogen and oxygen unite to 
form water, the combination takes place according to valence, as 



1 8 AGRICULTURAL CHEMISTRY 

follows : 2 atoms of H -\- i atom of equal i molecule of water, 
or 2H -f- O = H 2 0. An atom of O weighs 16 times as much as 
an atom of H. Two atoms of H and i atom of O weigh 18 times as 
much as an atom of H. The molecular weight of water is 18. 
Sixteen of these 18 parts, by weight, are O, or 16/18 are oxygen, 
which is 88.88 per cent.; 2/18, or 11.12 per cent, being H. In the 
production of water, H and O always unite in this proportion. If, 
for example, 20 grams of O and 2 grams of H were brought to- 
gether, only 16 grams of O would enter into chemical combination 
with the 2 grams of H, and 4 grams of O would be left uncombined. 
The amount of H required to combine with 20 grams of O would 
be obtained from the following proportion, — 2 : 16 : : x : 20, or 
x = 2 -5 grams of H. 

Problem 2. — (1) Calculate the per cent, by weight of C and O in 
C0 2 . (2) Calculate the per cent, of Fe and O in Fe 2 3 . (3) 
Calculate the per cent, of O in KC10 3 . 



CHAPTER III 
Laboratory Manipulation 

22. Importance of Laboratory Practice. — Laboratory 
practice is an essential part of the study of chemistry. 
Many of the important facts and laws of chemistry are 
capable of being demonstrated by the student, and the 
laboratory practice assists in developing more perfect 
ideas in regard to the composition of substances. The 
hand, the eye, the nose, and, to a less extent, the ear, 
are all called into use in the laboratory, and this results 
in a balanced education of the senses. Neatness is abso- 
lutely necessary for success in laboratory work. An ex- 
periment performed in a slovenly way, with dirty and 
poorly connected apparatus, and poor mechanical manip- 
ulation, fails to give the right impression or results. 

When laboratory work is in progress it should receive 
the student's entire attention. The directions for the 
experiments should be carefully followed. The appara- 
tus should always be put together as directed, and be- 
cause of the danger of accident, the student should never 
take the risk of connecting apparatus in an original way, 
or of using for the experiment, materials other than those 
directed. The student should never attempt to experi- 
ment for himself in combining chemicals. 

23. Names and Uses of Apparatus. — The various 
pieces of apparatus used in the experiments are shown in 
Plates I and II. Number 23 shows the common Bunsen 
burner, and at the right, the wing-top attachment, used 



20 AGRICULTURAL CHEMISTRY 

in bending glass tubes. Number 24, Plate II, is an iron 
ring-stand with three rings, and No. 25 is a single clamp. 
The iron stand with rings is used for supporting appara- 
tus, particularly the sand-bath (19) in which is a thin 
layer of sand. The evaporating dish (5), beaker (12), 
and flask (26) are all supported in the various experi- 
ments upon the sand-bath and iron ring-stand. In the 
cutting of glass tubes and the perforation of corks, the 
two files (1 and 2) are employed. Test-tube (13) is used 
extensively in the laboratory, and when heated it is sup- 
ported in the test-tube clamp (18). This test-tube clamp 
is held in the hand. The test-tube is cleaned with the 
test-tube brush (17) and when not in use is placed in the 
test-tube rack (14). When solutions are filtered, the 
funnel (15) is used, and is supported in the wooden 
stand (21). Substances are pulverized or mixed in the 
mortar (16) which is supplied with a pestle. The vari- 
ous gases, as oxygen, hydrogen, and nitrogen, are col- 
lected in the small cylinder (10), and in some of the ex- 
periments, the large cylinder (11) is used. The iron 
spoon (8) is used for the ignition of substances. The 
crucible tongs (3) are for handling pieces of apparatus 
when hot. The other pieces of apparatus, Woulff bottle 
(7), water-bath (4), tripod (22), Hessian crucible (20), 
wide-mouthed bottle, (9), and the ground glass plate 
with a hole, are used in various ways in the different ex- 
periments. Glass rods, a thistle-tube, a pneumatic trough, 
and small squares of plain glass complete the set of appa- 
ratus. A few pieces, used only occasionally, are obtained 
from the instructor at the time the experiments are per- 
formed. 




PLATE I.— Apparatus used in experiments 



,;. \§10 




" 1 



13 



\ 



C=J 




(g&G^ 



sv, 



|^-D|-dq/ ra 



£5 




Plate II.— Apparatus used in experiments. 



LABORATORY MANIPULATION 



21 



The student should take an inventory of his apparatus 
as soon as assigned a place in the laboratory. In case 
any of the pieces are broken or missing, the attention of 
the instructor should be called to them. Always, at the 
close of each da3 r 's work, the apparatus should be 
cleaned, placed in the desk, and the desk locked. The 
apparatus and desk should always be kept in a neat and 
orderly condition. Untidiness is a frequent cause of 
failure in laboratory work ; neatness and careful atten- 
tion to details are necessary to success. 

24. Cutting Glass Tubing. — Lay the glass tube on the 
top of the desk or any fiat surface. Draw a sharp three- 
cornered file across it two or three times, always on the 
same place at wmich it is to be broken, until a scratch is 
made through the annealed surface of the tubing. Take 




Fig. 1.— Breaking glass tubing. 

the tube in the hands with fingers and a thumb on each 
side of the scratch (see Fig. 1). The scratch should be 
nearly between and on the side opposite the thumbs. 
Pull the hands toward the body as if bendiug the tube, 



22 



AGRICULTURAL CHEMISTRY 



and at the same time press outward with the thumbs. 
This causes a square break of the tube. The cut ends of 
the tubing should then be held in the outer portion of the 
flame until the rough edges are annealed. 

25. Bending Glass Tubing. — Place the wing-top at- 
tachment on the burner. Hold the tube in the upper 
part of the flame as shown in the illustration (Fig. 2), 




Fig. 2. — Bending glass tubing. 

and rotate so that all parts are heated alike. When the 
tubing becomes red and readily yields, it can be bent in 
almost any form desired, but if overheated it becomes too 

soft and collapses. It is always 
best to bend without removing 
from the flame. A little prac- 
tice with pieces of old tubing will 
soon give the necessary experi- 
ence. Avoid twisting or rapid bending of the tube. 
Make all bends on the same plane and aim to make well 
rounded joints as shown in Fig. 3. 

26. Perforating Works. — Select a cork of suitable size 
for the test-tube or flask used. New corks should always 




Fig. 3.— Bent tube. 



LABORATORY MANIPULATION 



23 



be rolled in the cork press. With the small pointed end 
of the round file make a hole through the center of the 
cork, or a little to one side if directed to do so. This 
hole should be perpendicular to the surface of the cork. 
In making a hole, the cork should be held in the left hand, 
and the larger end should be placed against the edge of 
the desk. The file should be held in the right hand, and 
only enough pressure exerted to perforate the cork. By 
means of the round end of the file, the opening thus made 
is enlarged until the desired size is obtained. The hole 
should be a suggestion smaller than 
the tube it is to receive, which can be 
inserted easily if well annealed and 
wet. When inserting a tube in a 
cork, never push the tubing toward 
the palm of the hand, or use too much 
pressure ; otherwise severe cuts may 
be received from breaking of the glass. 
Hold the cork in the left hand as 
shown in Fig. 4, and then with the right hand carefully 
insert the tube. 

27. Weighing. — In this work, the metric system of 
weights and measures is employed, and it is taken for 
granted that the student is familiar with the system ; if 
he is not, he should review the subject as given in any 
ordinary arithmetic. 

Note.— 1 kilo =2.2046 lbs. (avoirdupois). 
1 oz. = 28.35 &ms. 
1 lb. = 453.59 gms. 
1 liter = 1.05708 TJ. S. quart. 
1 inch = 2.54 centimeters. 
1 meter = 39.380S inches. 




Fig. 4. — Inserting glass 
tube into cork. 



2 4 



AGRICULTURAL CHEMISTRY 




The small balance used for weighing materials in these 
experiments is shown in Fig. 5. In case 5 grams of a 
material are to be weighed, prepare counterpoised papers, 
about 3 by 4 inches in size ; that 
is, two pieces of paper of exactly 
the same size to be placed on op- 
posite sides of the balance. If 
they do not weigh alike, remove 
small pieces of paper from the 
heavier pan, until the needle 
moves nearly as many divisions 
on one side of the scale as on the 
other. Then place, with the for- 
ceps, the 5-gram weight on the 
Fig. 5.— Balance. right-hand pan of the balance. 

Do not handle the weights with the fingers. By means of 
the scoop or spoon provided for the purpose, add to the 
paper in the left-hand pan of the balance, enough of the 
material that is to be weighed to counterpoise the 5-gram 
weight. If any of the substance has been spilled it should 
be cleaned up at once. The weight should be replaced in 
the weight box and the forceps rettirned to their proper place. 
If the weights are lost, a charge is made to cover the ex- 
pense of their replacement. No substance except a piece 
of metal, as copper or lead, should ever be placed in direct 
contact with the balance pan. Liquids are never weighed, 
but always measured. Too much care and neatness can- 
not be exercised in weighing. 

28. fleasuring Liquids. — For purposes of measuring, 
cylinders or graduates are employed (Fig. 6). A large 



LABORATORY MANIPULATION 



25 




Fig. 6. 
Measuring 
cylinder. 



test-tube, when filled with water, holds from 60 to 65 cc. 
Take a measuring cylinder or graduate (Fig. 6), measure 
out 5 cc. of water, and transfer to a large test- 
tube. Note the quantity, and then pour it 
out. Now draw water directly into the test- 
tube until you have approximately the same 
amount, then measure it. Repeat this opera- 
tion until you can judge with a fair degree of 
accuracy the part of a test-tube filled by 5 cc. 
Then repeat the operation, using 10, 15, 20, 
and 25 cc. portions, until the eye has become 
reasonably familiar with these approximate 
and relative amounts ; so that, if at any time 
a graduate is not at hand, the amounts can be 
estimated with the eye accurately enough for practical 
purposes. 

29. Obtaining Reagents from Bottles. — Take the bot- 
tle from the shelf, remove 
the stopper, holding it be- 
tween the first and second 
fingers of the right or left 
hand (Fig. 7). Hold the 
test-tube or vessel that is 
to receive the reagent in 
the other hand. Pour out 
the liquid slowly until the 
desired amount is obtained. 
Because of danger of con- 
Fig. 7. -Pouring liquid from bottle, tamiuating the reagents, it 
is always better to pour the liquid slowly and secure the 




26 



AGRICULTURAL CHEMISTRY 



right amount at first rather than to pour back from the 
receiving vessel. Replace the test-tube in the stand or 
receiver on the desk ; then, before inserting the stopper, 
touch it to the neck of the bottle to catch the few drops 
on the edge, to prevent them from streaking down the 
sides of the bottle, and on to the shelf. Be sure to replace 
the bottle on the shelf in its proper place. Much an- 
noyance and delay is caused by not returning the bottles 
to their proper places. 

30. Filtering — Place the funnel on the arm of the 
wooden stand. Fold a filter-paper so as to make a semi- 





Fig. 3. 



Fig. 9. 
Folding filter-paper. 



Fig. 10. 



circle (see Figs. 8 and 9). Fold the paper again, 
forming a quadrant (Fig. 10) . Then 
open it as shown in Fig. 11. 
Place the filter-paper in the funnel, 
using a little water to make it ad- 
here to the sides. Place a beaker 
or cylinder under the funnel so as 
to collect the filtrate, or liquid which 
passes through the filter-paper (Fig. 

12). Pour the material to be filtered into the filter- 




Fig. 11.— Folded filter- 
paper. 



LABORATORY MANIPULATION 



27 



paper in the funnel. Do not fill the filter too full. An 
eighth of an inch or so should always be left between the 
surface of the liquid and the edge 
of the paper. The stem of the 
funnel should always be left against 
the side of the beaker or cylinder so 
as to avoid spattering. The ma- 
terial left on the filter-paper is 
called the precipitate or residue. 

31. Laboratory Note-book. — 
Each student should keep a careful 
record of his laboratory work. The 
note-book should be complete and 
should represent the student's in- 
dividual work. With each experi- 
ment a number of questions are 
asked, and the record of the experi- 
ment should embody the answers 
to these questions. Do not make 
short answers, as "yes" and "no," 
but make a complete statement, 
giving an intelligent answer to the 
question. Do not copy the laboratory directions into 
your note- book, but state briefly and concisely , (1) what 
the experiment is about, (2) the materials used, (3) the 
apparatus employed, (4) what you have observed in ma- 
king the experiment, (5) the chemical and other changes 
that have taken place, and finally what the experiment 
proves. In writing up the note-book, it is not necessary 
to separate the topics, but all the questions should be 




Fig. 12.— Filtering. 



28 AGRICULTURAL CHEMISTRY 

numbered and answered in the order asked. Write out 
each experiment at the time it is performed ; and while 
the work is in progress, watch it and think about it. Do 
not leave or neglect an experiment. When the experi- 
ments are performed as called for from day to day, the 
labor of preparing the daily recitation is considerably 
lessened, and less effort is required to obtain a clear idea 
of the subject. The note-book should be kept in a neat 
and orderly way. Careful attention should be given to 
spelling, English, and punctuation. Always have the 
note-book in condition for examination if the books are 
called for without notice. The instructor will mark all 
errors, and the student should correct these errors. A 
note-book with errors that have been corrected, represent- 
ing the student's individual work, is much to be preferred 
to a note-book, copied from some other student, and hav- 
ing but few errors. Each student has an individuality 
which always marks his work, and whenever copying of 
experiments is resorted to, it is detected by the in- 
structor. The student who copies from some one else 
only cheats himself, and usually fails to pass his exam- 
inations. 

32. Breaking of Apparatus. — If due care is taken in 
performing the experiments, there will be but little break- 
age of apparatus. In case an accident occurs, clean up 
the broken pieces at once and place them in the waste jar. 
If a liquid is spilled, wipe it up with a sponge, using 
plenty of water. If a strong acid is spilled, a little dilute 
ammonia should be used in the final washing. No com- 
bustible materials should be placed in the desk, and the 



LABORATORY MANIPULATION 29 

student should throw burned matches and splinters into 
the receptacles provided for the purpose. 

33. Care of Sinks and Plumbing.— Do not throw waste 
matter of any description, as paper, glass, matches, etc., 
into the sinks. Large waste jars, for such materials, are 
provided under every sink and elsewhere. Everything 
liable to clog the drains must be thrown into these jars. 
Liquids containing acids may be safely thrown into the 
sinks, provided a stream of water is kept running at the 
same time to dilute and wash out the acids. When acids 
are poured into the sinks, care should be taken to prevent 
spattering of the liquid, as severe burns are sometimes 
received when the liquid is not properly poured from the 
vessel. If directions are followed no accidents can occur. 
Do not fill the sinks too full. The water should never be 
allowed to come to within 2 inches of the top of the 
sinks. If the sinks overflow they cause much damage to 
the rooms below. Students who disregard the regula- 
tions in regard to plumbing and the use of sinks, will be 
held responsible and must pay for any damage caused by 
carelessness or negligence. 

34. How to Accomplish the Best Results in the Lab- 
oratory. — In order to accomplish the best results, the 
student, while in the laboratory, should endeavor to use 
his time profitably and economically. He should obtain 
a clear idea of what he is to do, and then doit to the best 
of his ability. If the experiment is not a success, repeat 
the work. Never pass over an experiment that offers 
difficulties in performing. Much valuable time can be 
saved by a brief study of the day's work before going 



30 AGRICULTURAL CHEMISTRY 

into the laboratory. While the work is in progress, the 
student should give it undivided attention, and make an 
effort to learn as much as possible from the experiments 
performed. 



CHAPTER IV 
Oxygen 

35. Occurrence. — Oxygen is the most abundant element 
in nature. About one-fourth of the air, by weight, is 
free or uncombined oxygen. It enters into the composi- 
tion of water, rocks, and minerals, and plant and animal 
bodies. Seven-eighths of water and 
one-half of the solid crust of the 
earth are oxygen in combination with 
other elements. Oxygen is also 
present in all animal and plant tis- 
sue, making up a large portion of 
the weight of these bodies. 

36. Preparation. — Oxygen can 
be prepared from a number of ma- 
terials, as oxid of mercury, oxid of 
iron, and potassium chlorate. When 
made in small amounts in the lab- 
oratory, it is usually prepared by 
heating potassium chlorate, a com- 
pound composed of the elements 
potassium, chlorin, and oxygen. 
The oxygen is separated by means 
of heat, the process being as follows: 

Experiment 1. — Anneal the end of a 
piece of glass tubing, 2 1/2 or 3 feet long. 
Make a bend nearly at right angles to the Fig- 13-— Delivery tube, 
tube, about 3 inches from one end. Then make a second bend 
of 2 1/2 or 3 inches on the opposite end of the tube nearly at right 



AGRICULTURAL CHEMISTRY 



angles, and in an opposite direction from the first bend (Fig. 13). 
Fit to the test-tube a cork, perforated as directed in Section 26, and 
insert the delivery tube. Fill the pneumatic trough nearly full of 
water, and place in it the free end of the delivery tube (Fig. 14). 
Weigh out 5 grams each of potassium chlorate (KC10 3 ) and man- 




Fig. 14.— Preparation of oxygen. Pneumatic trough. 

ganese dioxid (Mn0 2 ). Mix on a sheet of paper, and place the 
mixture in a test-tube. See that the test-tube is perfectly dry, both 
inside and out. Fill the cylinders with water, cover with glass 
plates and place them inverted on the shelf of the pneumatic trough. 
With a medium-sized flame, apply heat cautiously to the test-tube. 
The flame should be moved from time to time, and not allowed to 
strike just one part of the test-tube, otherwise the glass will melt, 
and the test-tube collapse. As soon as bubbles of gas are given off 
freely from the water, place the end of the delivery tube so that 
the gas is collected in one of the cylinders. When a cylinder 
is filled, cover it with one of the glass plates, while the mouth of 
the cylinder is still under water. It can then be placed upright 
upon the desk, and another cylinder filled with O. After collect- 
ing three or four cylinders of gas, remove the end of the delivery 
tube from the water, and then remove the flame. Do not remove 
the flame while the end of the delivery tube is under water, or a 
vacuum will be formed, and the water will rush back into the test- 
tube. Tests should be made with the O as follows : 

(1) Light a splinter and place it for a moment in one of the cyl- 
inders of oxygen (see Fig. 15) ; remove it ; extinguish the flame, 



OXYGEN 



33 




and while the splinter is still glowing, thrust it into the cylinder 
again. Observe the result in each case. (2) Put a small piece of 
sulfur, a little larger than a grain of wheat, into the iron or defla- 
gration spoon ; ignite in the flame, and 
then thrust into another cylinder of O. 
Observe the result. (3) Take a piece of 
bright fine iron wire or watch-spring, and 
make it into a spiral with a loop at one 
end. Warm the wire by holding it near 
the flame, then hold the loop for an in- 
stant in the flame and dip it into some 
sulfur which has been placed on a piece 
of paper. Hold again in the flame for a 
moment and then place at once in the 
third cylinder of O . In order to insure 
the success of this experiment, the wire 
should be very fine, free from rust, and 
held in the flame only long enough to 
start ignition, and then placed in the 
cylinder. 

Questions. (1) Where does the O in the cylinder come from ? 
(2) What caused it to separate from the compound? (3) What is 
the appearance of O ? (4) Compared with air, is it a light or heavy 
gas? (5) What caused the splinter to burn and to rekindle ? (6) 
What product was formed when the splinter was burned? (7) 
What caused the sulfur to burn? (8) What product was formed 
when the S was burned ? (9) Why do these materials burn differ- 
ently in O than in air? (10) What caused the iron to burn, and 
what was formed ? (11) Is O combustible ? (12) Is O a supporter 
of combustion ? (13) What compounds are always formed by the 
union of O with an element? (14) Give the properties and char- 
acteristics of O as observed from this experiment. 

The oxygen in potassium chlorate is not held in firm chemical 
combination, and when thesubstauce is heated, first a portion, and 
finally all of the oxygen is given off. The manganese dioxid is 
used because of its physical action upon the potassium chlorate, 

3 



Fig. 15.— Testing oxygen 
with burning splinter. 



34 



AGRICULTURAL CHEMISTRY 



enabling the oxygen to be given off more easily. The change 
which takes place is expressed by the equation: KC10 g = KC1 + 30. 
The products of the reaction are potassium chlorid and oxygen. 




Fig. 16. — Preparation of oxygen, using sink in place of pneumatic trough. 
The oxygen is collected in the cylinders, while the potassium chlo- 
rid remains with the manganese dioxid in the test-tube. 

37. Properties of Oxygen. — Physically considered, 
oxygen is a colorless, odorless, and tasteless gas, about 
16 times as heavy as hydrogen. It is slightly soluble in 
water, and, when subjected to a low temperature and a 
high pressure, it is liquefied. Chemically, oxygen unites 
with all common elements to form oxids. It is not com- 
bustible, but is a supporter of combustion. When the 
burning splinter was thrust into the cylinder of oxygen, 
the carbon and hydrogen of the wood united with the 
oxygen in the cylinder, forming carbon dioxid and water. 
When substances unite with oxygen they are oxidized, 
that is, oxygen is added to the material. An oxid is a 
compound of oxygen and any other element. When sul- 
fur is burned, it unites with oxygen, forming sulfur di- 



OXYGEN 35 

oxid, S0 2 . Other elements, as phosphorus and iron also 
unite with oxygen, forming oxids. Different elements 
unite with oxygen at different temperatures. Phosphorus 
and sulfur combine with oxygen at a comparatively low 
temperature, while carbon and iron require a higher tem- 
perature. The sulfur and the splinter of wood burned 
more brilliantly in the oxygen than in the air because air 
is diluted with other gases and elements and is not pure 
oxygen. Oxygen is more active at a high than at a low 
temperature. 

The oxidation of some of the elements and compounds 
results in the production of light and heat ; this is com- 
monly called combustion. Oxygen forms stable com- 
pounds with many of the elements. It has such affinity 
for some elements, as aluminum and carbon, that it is 
separated from them with difficulty. With other ele- 
ments it forms less stable compounds. When a substance 
contains oxygen, it does not necessarily follow that it is 
combustible, because it may be the product of combus- 
tion as carbon dioxid or sulfur dioxid. When an ele- 
ment, as oxygen, enters into chemical combination, it 
loses its identity or individuality as an element. The 
oxygen that is present in the minerals forming the crust 
of the earth, and in plant and animal tissues, is not free 
but combined with other elements. 

38. Importance. — Oxygen takes an important part in 
life affairs, and is necessary to the existence of plant and 
animal bodies. The combustion of wood, coal, and other 
fuel is due to the oxygen of the air. The production of 
heat in the body is due to the oxidation of food, and many 



36 AGRICULTURAL CHEMISTRY 

of the chemical changes which take place in the soil are 
dependent upon this element. Because of its wide distri- 
bution in nature, it is not given such economic considera- 
tion as are other elements, but it is one of the most im- 
portant, and is as necessary for life as other food. 

Problem I. — How many pounds of oxygen are required to com- 
bine with 25 pounds of pure carbon ? When carbon is burned, 1 
part of C (called an atom) unites with 2 parts of O (2 atoms of O) 
to form the compound C0 2 . This is expressed by the equation 
C -f 2O = C0 2 . The atomic or least combining weight of carbon is 
12 and of O is 16; one part by weight of C weighing 12 unites with 
2 parts by weight of O, each part weighing 16 ; or 12 parts by 
weight of C unite with 32 parts by weight of O. If the parts are 
designated pounds then 25 pounds of C will require proportionally 
as much O as do 12 pounds of C. This amount can be determined 
by a simple proportion. 

C : O : : C :0 
12 :32 : : 25 :x. 
By solving this proportion, x, or the required amount of O to com- 
bine with 25 pounds of C, is found to be 66 2/3. 

In the solving of chemical problems some of the most 
common errors are : ( 1 ) Failure to write properly the 
formulas of the compounds used, or the equation repre- 
senting the chemical reaction that takes place. This 
error causes the wrong number of parts of elements or 
compounds to be taken in the proportion. (2) Failure 
to make proper use of the combining weights of the ele- 
ments. (3) Failure to combine properly the weights so 
as to form a true proportion. It should be remembered 
that after the writing of the equation and weights, the 
problem becomes simply one of arithmetic. 

Problem 2. — How many pounds of C0 2 are produced when 25 
pounds of carbon are burned ? 

Problem j. — How many pounds of carbon are necessary to com- 
bine with 25 pounds of O in forming C0 2 ? 



CHAPTER V 
Hydrogen 

39. Occurrence. — Hydrogen is found in nature in com- 
bination with other elements, entering into the composi- 
tion of water, animal and plant tissues, and some min- 
erals. It is never found in a free state, except as given 
off in traces with volcanic gases. Hydrogen is also found 
in all acids and many other compounds. 

40. Preparation. — In the laboratory, hydrogen is usu- 
ally prepared by treating a metal with an acid, which 
contains hydrogen ; the metal replaces the hydrogen of 
the acid and the hydrogen is then liberated as a free gas. 
When zinc and hydrochloric acid are employed, the re- 
action which takes place is as follows : Zn -f- 2HCI = 
ZnCl 2 -f- 2H. Two molecules of hydrochloric acid are 
required in the reaction because zinc has a valence of 2, 
and whenever zinc enters into chemical combination, it 
must take the place of two monovalent atoms. The 
compound, ZnCl 2 , zinc chlorid, contains one atom of zinc 
and two atoms of chlorin. 

Experiment 2. — Arrange the apparatus as shown in Fig. 
17. Use the small two-necked Woulff bottle, and in one of the 
necks insert a tight-fitting cork with a thistle tube. In the 
other neck insert a cork carrying a delivery tube. Place about 
20 grams of zinc, Zn, and 25 cc. of water in the Woulff bottle. 
The thistle tube should pass below the surface of the water to 
prevent the escape of gas. Fill two or three cylinders with 
water for collecting the gas. The corks carrying the delivery 
tube and the thistle tube should fit tightly, otherwise the H is 



38 



AGRICULTURAL CHEMISTRY 



easily lost. When all is ready, add, through the thistle tube, 
about 15 cc. concentrated hydrochloric acid (HC1), and then 
sufficient water to carry the acid out of the trap of the thistle 
tube. Do not apply any heat whatever. Do not collect any gas 
until the generator has been going for about two minutes, and do 




Fig. 17. — Apparatus for preparation of hydrogen. 
not attempt to light the gas as it issues from the generator. Col- 
lect one or two cylinders of gas, adding more acid if necessary, 
always keeping the cylinders covered, mouth downward, because 
H is a light gas, and will readily escape if the cylinders are 
placed right side up. 

When working with hydrogen in the laboratory, the 
student should always exercise care, because mixtures of 
hydrogen and oxygen are very explosive. Only a spark 
or a near-by flame is necessary to bring about an explo- 
sion. 

Make the following test with hydrogen : Thrust a burn- 
ing splinter into the mouth of the cylinder of hydrogen, 
as shown in Fig. 18. 

Questions. (1) What is the color ofH? (2) Odor? (3) Is 
it a light or heavy gas ? (4) Does it support combustion? (5) 



HYDROGEN 



39 



Is it combustible? (6) What is formed when H is burned? 
(7) How do you know that this product is formed ? (8) From 
what compound was the H obtained ? (9) What caused the H 
to be liberated from this compound ? (10) Why are mixtures of 




Fig. iS. — Thrusting burning splinter into hydrogen. 

H and O very explosive? (11) What other acids could be used 
in the preparation of H ? (12) What other metals could be used 
in the preparation of H ? (13) Give the equation for the reac- 
tion of the Zn and HC1. (14) What do these tests prove in re- 
gard to the character and properties of the element H ? 

41. Properties. — Physically, hydrogen is characterized 
as a colorless, odorless, and tasteless gas. It is the 
lightest in weight of any of the elements, and for that 
reason is taken as the standard for the atomic weights. 
At a low temperature, and under pressure, hydrogen can 



4 o 



AGRICULTURAL CHEMISTRY 



be liquefied; with greater difficulty, however, than any 
other element. Hydrogen is 14.43 times lighter than air. 
A liter of hydrogen, under standard conditions of tempera- 
ture and pressure, weighs 0.08961 gram. Chemically, 
hydrogen is characterized as combustible, but not a sup- 
porter of combustion. It readily combines 
with many other elements, particularly oxy- 
gen, with which it forms water. When 
hydrogen and oxygen unite to form water, 
a reaction takes place which causes a 
contraction in volume. 
Two volumes of hy- 
drogen and one vol- 
ume of oxygen unite 
to produce two vol- 
umes of water-vapor or 
steam. When hydro- 
gen and oxygen unite, 
there is always an ex- 
plosion, due to contrac- 

Fig. 19.— Preparation of hydrogen, using a tion in volume. That 
wide-mouthed bottle and sink in place of 
a Woulff bottle and pneumatic trough, water IS produced when 

hydrogen is burned, can be demonstrated by placing a dry 
test-tube over a flame of hydrogen. The interior of the 
test-tube will become covered with moisture. Hydrogen 
does not unite with all elements as readily as does oxygen. 
When hydrogen is burned, the flame is nearly colorless be- 
cause the combustion is complete, and there are in the 
flame no solid particles heated to incandescence. Hydro- 
gen produces an exceedingly hot flame, and, when mixed 




HYDROGEN 4 1 

with oxygen in the right proportion, as in the oxyhydro- 
gen blowpipe, a high temperature is secured. 

42. Importance. — Hydrogen is one of the essential ele- 
ments for the formation of compounds present in plant 
and animal tissues, but because of its extreme lightness 
it never makes up a large portion by weight of a mate- 
rial. As a free element, it takes no part in life processes, 
but when combined with water, and in other forms, as in 
food materials where it is united with carbon and oxy- 
gen, it forms an essential part of compounds which are 
of much importance for animal and plant life. 

Problem 1. — How many pounds of H will 100 pounds of Zn 
liberate when it is acted upon by H 2 S0 4 ? 

Problem 2. — How much. ZnCl 2 is formed when 100 pounds of 
Zn are acted upon by HC1 ? 



CHAPTER VI 
Nitrogen 

43. Occurrence. — Nitrogen occurs abundantly in a free 
state in the air, nearly four-fifths by weight being uncom- 
bined nitrogen. It also forms a part of some of the com- 
pounds which make up animal and plant tissues, where 
it is in chemical combination with carbon, hydrogen, and 
oxygen. Nitrogen is present also in the soil, forming a 
part of the decaying organic matter ; it is one of the ele- 
ments of ammonia gas and ammonium compounds, and is 
present in combination with other elements, as in nitrates. 

44. Preparation. — Nitrogen is usually prepared from 
air by removing the oxygen with which it forms a me- 
chanical mixture. Since air is composed of both oxygen 
and nitrogen, if the oxygen in a given volume of air, as 
in a cylinder, is chemically united with phosphorus or 
carbon, forming soluble products, there is a residue of 
nitrogen left in the cylinder. Nitrogen produced in this 
way is not pure, but contains traces of other elements and 
compounds. For experimental purposes, it may, how- 
ever, be considered as nitrogen. Nitrogen can also be 
produced from its compounds, as by the removal of the 
hydrogen from ammonia gas. The method of prepara- 
tion in the laboratory is as follows : 

Experiment 3. — Insert a long pin through the center of a 
large flat cork. Fasten a short piece of candle to the cork by 
means of the pin. Nearly fill the pneumatic trough with water. 
Light the candle and float it upon the surface of the water. In- 
vert the large cylinder over the candle, having the mouth of the 



NITROGEN 



43 



cylinder just below the surface of the water, as shown in Fig. 
20. After the candle is extinguished, remove it by thrusting the 
hand through the water into the cylinder without admitting any 




Fig. 20. — Preparation of nitrogen, 
air. While still under water, cover the cylinder with a glass plate 
and remove from the trough. Then make the following tests : 

( 1 ) Insert a burning splinter into the cylinder of N. Observe 
the result. (2) Place a little sulfur in the deflagration spoon, 
ignite, and insert in the cylinder of N. Observe the result. 
(3) With a ruler, measure the height of the cylinder and the 
amount of water left in the cylinder. 

Questions. (1) What is the color of N? (2) Odor? (3) Com- 
pared with air is it a heavy or light gas? (4) Is it combustible? 
(5) Does N support combustion ? (6) Is N an active element ? 
(7) What portion of the cylinder is filled with water in the 
preparation of N ? (8) What portion of the cylinder is filled 
with N? (9) What portion of the cylinder did the O occupy ? 
(10) What becomes of the products of the combustion of the 
candle? (11) What do these experiments prove in regard to 
the element N ? (12) Complete the following table : 

Name of Combin- Combus- Supporter of Where 

element. Symbol, ing wt. Color. Taste. Odor, tible. combustion, found. 

Oxygen 

Nitrogen 

Hydrogen 

When the candle is burned, the oxygen of the air in the cyl- 



44 AGRICULTURAL CHEMISTRY 

inder unites with the carbon and hydrogen from the candle and 
forms carbon dioxid and water. The C0 2 is soluble in water, 
and the gas that is left is mainly nitrogen. The com- 
bination of the oxygen with the carbon causes a partial vacuum 
to form, and this results in the water rising in the cylinder. If 
great care is taken in performing the experiment, it will be found 
that the water will fill about one-fifth of the volume of the cylin- 
der, occupying the space of the oxygen which has been com- 
bined with carbon. When all of the oxygen in the cylinder is 
combined with the carbon, the candle is extinguished because of 
lack of oxygen for combustion. 

45. Properties of Nitrogen. — In general, the physical 
properties of nitrogen, except weight, are somewhat like 
those of hydrogen and oxygen, inasmuch as when pure, 
it is colorless, tasteless, and odorless. It is about 14 
times as heavy as hydrogen, and only slightly soluble in 
water. At a low temperature and under pressure, it is 
liquefied, and at a still lower temperature and under higher 
pressure, it is solidified. 

Chemically, nitrogen is unlike either hydrogen or oxy- 
gen. It is an inactive gas; it is neither combustible nor 
a supporter of combustion. When in the free state, it is 
one of the most inactive of all the elements, and will com- 
bine directly with only a few. When nitrogen enters into 
combination with other elements, particularly with car- 
bon and hydrogen, forming the organic compounds, it 
has a tendency to make a weak link in the combination, 
and will readily split off and form simpler products. In 
the air, it serves the purpose of diluting the oxygen. No 
other element could perform this function as well as ni- 
trogen. If the air were composed of pure oxygen, all 
combustion would be carried on in a rapid and wasteful 



NITROGEN 45 

way. Nitrogen is not a poisonous gas, but if an animal 
were compelled to breathe pure nitrogen, it would die 
because of the lack of oxygen. Some of the compounds 
of nitrogen decompose with violence, causing explosions. 
Nearly all of the explosives, as gunpowder, nitroglycerin, 
and guncotton, are compounds of nitrogen. 

46. Importance. — The compounds of nitrogen take an 
important part in animal and plant life. In combination 
with carbon, hydrogen, and other elements, it forms the 
nitrogenous compounds present in plant and animal bod- 
ies. These compounds are called the organic nitrogenous 
compounds because they are capable of undergoing com- 
bustion, and produce volatile and gaseous products when 
burned. 

In the study of the chemistry of foods, and of soils and 
fertilizers, the element nitrogen is given a prominent 
place. This is because it is one of the most expensive 
elements in commercial fertilizers, and foods which 
contain the nitrogenous compounds are the most ex- 
pensive. Although nitrogen is found abundantly in the 
air, it is made use of as a plant food in an indirect way by 
only a limited number of plants. Nitrogen forms a large 
number of important compounds, as ammonia, nitrates, 
nitrites, amids, and the complex organic compounds, pro- 
teids. Some of these compounds will be studied more in 
detail in future chapters. To the agricultural student, 
nitrogen is one of the most important elements because of 
the role which it plays in plant and animal economy. 

Problem 1. — Calculate the per cent, of N in NaNO s . 
Problem 2. — Calculate the per cent, of N in NH 3 . 
Problem 3. — Calculate the per cent, of N in (NH 4 ) 2 S0 4 . 



CHAPTER VII 
Carbon 

47. Occurrence. — Carbon is found in the free state 
only in limited amounts, but is present in nature mainly 
in combination with other elements. With the mineral 
elements and oxygen, it forms carbonates, such as calcium 
carbonate or limestone. With hydrogen and oxygen, and a 
few other elements, it forms a large number of compounds 
of which plant and animal tissues are composed. All sub- 
stances which char or blacken when burned contain this 
element in combination. Diamonds, coal, and graphite 
are forms of carbon in various degrees of purity. With 
oxygen, it is present in the air in small amounts as carbon 
dioxid. About half of the dry substance of wood and 
animal tissue is carbon. It occurs in nature in a great 
variety of forms. 

48. Preparation. — In the form of charcoal, it can be 
prepared from wood, by the application of heat in the ab- 
sence of air or oxygen, when a change known as destruc- 
tive distillation takes place. The hydrogen, oxygen, and 
nitrogen are expelled, while the black mass of impure car- 
bon and mineral matter is left. In the preparation of 
charcoal, the wood is piled and burned in suitable pits, 
which, after the combustion is well started, are covered 
with turf to protect the burning mass from the air. Char- 
coal can be produced on a small scale in the laboratory, 
in the following manner : 

Experiment 4. — Place two or three small pieces of wood in a 



CARBON 47 

Hessian crucible, and cover with sand. Heat the crucible until 
smoking ceases (see Fig. 21). Remove and examine the charcoal. 

Questions. ( 1 ) What are the principal elements present in wood? 
(2) What becomes of these various elements when the material is 
heated? (3) Why was the sand used in this ex- 
periment? (4) What becomes of the ash or mineral 
matter in the process of charcoal-making? (5) 
What is charcoal, and of what element is it prin- 
cipally composed? (6) Does charcoal have a crys- 
talline structure ? (7) What would be the result if 
sand were not used in the experiment ? (8) Give 
the equation for the combustion of carbon. (9) 
How can charcoal be made on a large scale ? 

Particles of carbon can also be obtained from a 
gas, candle, or lamp flame, by holding a piece of 
cold porcelain a little above the flame. Carbon, in 
the form of soot, is deposited in chimneys when 
fuel is burned with a poor draft. When combus- 
tion is complete, the carbon is oxidized, forming 
carbon dioxid. If a fire gives off a large amount Fig. 21.— Prepara- 
of dense black smoke, the carbon is not com- 
pletely oxidized, and consequently a loss of fuel value occurs. 

49. Properties. — Carbon is found in three forms in na- 
ture : as diamond, graphite, and amorphous carbon. 
The diamond is a pure form of crystallized carbon. It is 
capable of being burned the same as any other form of 
the element, and produces carbon dioxid. Diamonds of 
small size can be produced artificially by the cooling of 
graphite from molten iron. Graphite is also a crystalline 
form of carbon, but the crystals are of different shape and 
color from diamonds. It is soft, and is used quite exten- 
sively as a lubricant. As it does not burn as readily as other 
forms of carbon, it is used frequently for making cruci- 




48 AGRICULTURAL CHEMISTRY 

bles and for the linings of furnaces. It is a natural prod- 
uct and is also produced artificially by dissolving carbon 
in iron. There are a great many uncrystallized or amor- 
phous forms of carbon, as lignite and soft coal, lampblack, 
and charcoal. 

50. Coal. — All of the conditions under which coal has 
been produced are not known. It is supposed to be the 
result of the joint action of heat and pressure upon pre- 
historic forms of vegetation. Hard or anthracite coal is 
the purest form known, and yields the smallest amount 
of ash and unoxidized volatile products. Bituminous or 
soft coal is less pure as a larger amount of the carbon is 
present in chemical combination with the other elements, 
and when burned, the carbon is not as completely oxi- 
dized under ordinary conditions as is that of hard coal. 
Coal may contain a number of impurities, as sulfur and 
mineral matter. Cannel coal is a variety which contains 
a large amount of mineral oils. 

Lignite is vegetable matter which has only partially 
undergone the coal-forming process. It is less pure than 
soft coal, and is supposed to be an intermediate stage 
in the formation. Peat is vegetable matter which has 
undergone chemical changes under water. It is less pure 
than lignite. 

51. Allotropism. — An element which has the power to 
take on so many different physical forms as has carbon 
is called an allotropic element. Only a few elements have 
the properties of allotropism. 

52. Carbon as a Reducing Agent. — Carbon is used 
extensively for the reduction of minerals. The action of 



CARBON 49 

carbon as a reducing agent may be observed from the fol- 
lowing experiment : 

Experiment 5. — Mix thoroughly 2 or 3 grams of copper 
oxid (CuO) and an equal bulk of charcoal (animal charcoal). 
Place the mixture in a small test-tube and apply heat. Observe the 
result. 

Questions. ( 1 ) What is the bright red material produced in the 
test-tube? (2) What was the source of this material? (3) What 
caused the O to be separated from this compound? (4) What did 
it unite with ? (5) What was formed as the product ? (6) Write 
the reaction. (7) Why is carbon called a reducing agent? (8) 
What kind of an agent would CuO be called? (9) Why is carbon 
useful in separating minerals from their ores ? 

When carbon acts as a reducing agent, it unites with or abstracts 
the oxygen from the material reduced, forming C0 2 . The process 
is called reduction because the oxygen is abstracted. When oxy- 
gen is added to a material, the process is just reversed, and is called 
oxidation. When reduction takes place, oxygen is abstracted from 
a material. When oxidation takes place, oxygen is added. 

53. Combustion. — From the facts given in regard to 
oxygen and carbon, it is evident that combustion, in the 
ordinary sense, is simply the union of carbon with oxy- 
gen, and, as a result, light and heat are given off. If the 
process is a slow one, and heat without light is evolved, 
slow oxidation takes place. An example of slow oxida- 
tion is the rusting of metals. In slow oxidation, the total 
amount of heat evolved is the same as if the material un- 
derwent direct combustion. The regulation of drafts 
in stoves to influence the combustion of fuel so as to ob- 
tain the largest amount of heat, is based upon the simple 
laws of the combustion of carbon. 

A candle or gas flame well illustrates the law r s of com- 

4 



5o 



AGRICULTURAL CHEMISTRY 



bustion. The outer portion of the flame is a non-lumi- 
nous envelope of gases undergoing perfect combustion; 
within this is a layer of gases undergoing partial combus- 
tion, and constituting the light-giving part of the flame ; 
while in the center is a zone which is more perfectly cut 
off from the supply of air, and little or no combustion is 
taking place. The combustion of a gas or candle flame 
can be studied from the following experiment : 

Experiment 6. — Structure of the flame. Unscrew the top 
of a Bunsen burner and make a drawing showing how the burner 

works, and the workings 
of the orifices at the bot- 
tom of the burner. Re- 
place the parts of the 
burner, open the air-holes 
at the base, and light the 
gas. Hold a sheet of paper 
back of the flame and try 
to distinguish the three 
parts : ( i ) the outer non • 
luminous envelope of per- 
fect combustion ; (2) the 
inner luminous zone of 
partial combustion ; (3) 
the central blue cone of 




Fig. 22. — Combustion. 



unburned gas. Make a drawing of the flame. Press a piece of card- 
board or paper down upon the flame for an instant and remove it 
before it takes fire. Observe the result. Hold a piece of wire close 
to the burner and observe that at first the wire does not become red 
at the center of the flame. Thrust the head of a match into the 
center of the flame for an instant and then remove it. If this is 
done quickly, the match can be removed before combustion takes 
place. Place a piece of wire gauze above the flame as shown in Fig. 
23. Observe the result. Extinguish the gas. Hold the wire gauze 



CARBON 



51 



about an inch above the burner, then light the gas above the gauze 

(Fig. 22). 
Questions. ( 1 ) Why was a charred circle formed when the piece 

of paper was pressed down upon the flame ? (2) Why did the wire 

first redden near the outer 
portions of the flame and not 



js^gmm&?" 



y 



Fig. 23.— Combus- 
tion. 



at the center? (3) Why did 
the flame refuse to burn 
above the wire gauze, when 
the gauze was pressed down upon the flame? 
(4) When the gas was lighted above the gauze, 
why did it refuse to burn below ? ( 5 ) What is 
kindling temperature ? (6) What are the three 
conditions necessary for combustion? (7) What 
condition was lacking when the gauze was 
placed in the flame ? (8) Why does a flame give 
light when the air is excluded from the burner, 
and give but little light when the air vent is open ? (9) Does the 
amount of light which a flame produces indicate the amount of heat 
produced? Why? (10) What causes a flame to give light ? (11) 
Why do some materials, when burned, produce more flame than 
others? (12) What is spontaneous combustion ? (13) Explain how 
it is possible for clover or fodder to undergo spontaneous combus- 
tion in a barn. (14) What can be done to prevent spontaneous 
combustion? (15) Carbon, when burned, produces heat; limestone, 
CaC0 3 , contains carbon ; why is it not possible to use limestone for 
fuel? 

54. Spontaneous Combustion. — In order for a sub- 
stance to undergo combustion, it is not necessary for a 
match or flame to be applied to the material. As soon as 
a substance is heated to its kindling temperature, that is, 
the temperature at which it unites with oxygen, if in the 
presence of air, combustion takes place, called spontaneous 
combustion. Clover, when stored in the mow in a damp 



52 AGRICULTURAL CHEMISTRY 

condition, may undergo spontaneous combustion. The 
fermentation which takes place produces combustible 
gases which, at suitable temperature, ignite; 
the burning gases, in turn, ignite the carbon 
of the material. Substances containing a 
great deal of oil and materials of low kindling 
temperature, as carbon bisulfid, phosphorus 
and sulfur, under suitable conditions of tem- 
perature and air, readily undergo spontaneous 

Fig. 24— Candle combustion. 
flame. 3. Non- 
luminous cone, in case of fire, the laws governing combus- 

4. Luminous 

line. 5,6. outer tion should be taken advantage of. If the 

non-luminous 

envelope. fire is a small one, cut off the supply of air, 

and the fire is extinguished. This can be accomplished 
by the use of sand, wet blankets, or any material that 
will cut off the supply of air. In order for spontaneous 
combustion to take place, there must be (i) a combusti- 
ble substance, which (2) is heated to a suitable tempera- 
ture, and (3) in the presence of air. 

55. Carbon a Decolorizer and Deodorizer. — Wood and 
animal charcoal have the power of absorbing gases and 
some coloring materials from solutions. In the manu- 
facture of sugar, some of the impurities are removed by 
bone-black or animal charcoal filters, and in purifying 
water, charcoal filters are often used. The power of car- 
bon to abstract gases and coloring-matter is largely a 
physical property. In the soil, the carbon compounds de- 
cay and produce humus, which has some of the physical 
properties of charcoal to absorb gases and soluble bod- 
ies. 



CARBON 



53 



Experiment 7. — Place in a cylinder two grams of animal 
charcoal, and about 1 cc. cochineal solution diluted with 10 cc. 
water. Cover the cylinder with a glass plate and shake ; then 
pour the contents of the cylinder into a filter. If the first por- 
tion which filters, the filtrate, is not clear, pass it through the 
filter a second time. 

Repeat the experiment, using 2 cc. potassium sulfid solution, 
2 cc. hydrochloric acid, and 10 cc. water in place of the dilute 
cochineal solution. 

Questions. ( 1) What effect did the animal charcoal have upon 
the color of the solution? (2) What property does this show 
animal charcoal to possess ? (3) What was the result of filter- 
ing the potassium sulfid solution ? (4) What property does this 
show animal charcoal to possess ? 

56. Products of Combustion. — The carbon dioxid gas 
given off from either a candle or a gas flame can be col- 
lected by arranging an apparatus like that shown in Fig. 
25. A metal funnel is connected with a 
delivery tube which passes into a solution 
of lime water, Ca(OH) 2 , in a test-tube. 
The carbon dioxid given off from the 
flame passes into the lime water and by 
forming calcium carbonate causes it to 
become cloudy. Ca(OH) 2 + C0 2 = 
CaC0 3 + H 2 0. The carbon comes from 
the gas which undergoes combustion, and 
is combined with hydrogen as hydrocar- 
bons. That a candle produces its own 
combustible gases can be proved by col- 
lecting: some of the gas with a glass tube Fig. 25.— collecting 

° ° carbon dioxid from 

and rubber bulb as shown in Fig. 26. candle. 
This gas can then be burned as indicated in Fig. 27. 




The 



54 



AGRICULTURAL CHEMISTRY 




Fig. 26.— Obtaining unburned gas 
from candle. 



hydrogen of a gas or candle forms H 2 during combus- 
tion, and can be collected by passing the products of 

combustion through suitable 
absorbents. If a dry test-tube 
is held above the flame, a little 
moisture will collect on the 
sides of the test-tube. 

57. Compounds of Carbon. 
— Chemically, carbon forms a 
very large number of com- 
pounds, more, in fact, than 
any other element. The car- 
bon compounds present in 
plant and animal tissues are 
studied in a separate division 
of chemistry known as organic chemistry, while those 
compounds of carbon which are in com- 
bination with the mineral elements, as 
calcium, sodium, and potassium, are 
studied in inorganic chemistry. No well- 
defined boundary line, however, can be 
established between these two divisions 
of chemistry. 

58. Importance of Carbon. — The com- 
pounds found in plant and animal bodies 
contain carbon in larger amounts than 
any other element ; consequently the 
carbon compounds take a very import- 
ant part in animal and plant growth. 

Carbon is the element essential for the production of heat 




Fig. 27. — Combus- 
tion of gas from 
candle. 



CARBON 55 

when fuels and foods are oxidized. Commercially, the 
compounds of carbon are of great importance as they 
are found in foods, fuels, and in all animal and plant 
products. 

Carbon is found in the air in the form of carbon dioxid 
in sufficient amounts for the production of crops. It is 
also found in large amounts in human and animal foods; 
but because of its abundant presence, and its distribution 
in balanced form, it has not been considered to take such 
an important part economically in the production of plants 
as the element nitrogen. It is, however, equally impor- 
tant, although its natural distribution is such that it does 
not require as much effort, on the part of man, to obtain 
it as other forms of food materials. Nevertheless, the 
carbon compounds, particularly in food materials, should 
not be disregarded or considered of little or no importance 
because of their abundance. In the study of foods and 
the study of soils and fertilizers, some of the compounds 
of carbon are considered more in detail. 



CHAPTER VIII 
Water 
59. Chemical Composition. — That water is composed 
of hydrogen and oxygen in approximately the proportion 
of 2 volumes of H to i of O can be demonstrated by pass- 
ing a current of electricity through water and collecting 
the escaping gases. Oxygen will be 
liberated at the positive electrode, 
while hydrogen will be liberated at the 
negative electrode. That water is 
composed of 16 parts, by weight, of 
oxygen, to 2 parts, by weight, of 
hydrogen, can be demonstrated by 
passing hydrogen gas over copper 
oxid heated in a tube. The reaction 
which takes place is CuO + 2H = 
H 2 + Cu. If suitable provisions are 
made for weighing the oxid of copper 
used, and the water produced, it will 
be found that the weight of the 
water bears a definite relation to the oxid of copper 
reduced. For every loss of 16 grams of oxygen 
from the copper oxid, 18 grams of water are produced, 
showing that water is eight-ninths, by weight, oxygen. 

Experiment 8. — Distillation of water. Connect flask A (Fig. 
29) with the bent tube B to the condensing apparatus issued 
for this experiment. Place the distilling flask upon the sand- 
bath and in position as shown in Fig. 29. Fill the tank of the 
distilling apparatus, and half fill the flask, with water. Apply 




Fig. 28. — Electrolysis 
of water. 



WATER 



57 



heat to the flask, and reject the first portion of water that is dis- 
tilled. Distil about 25 or 30 cc. of water. 

Tests. (1) Thoroughly clean out your porcelain evaporating 
dish, if necessary using a little white sand for scouring, rinse 
with distilled water, and 
then by placing the evap- 
orator upon a sand-bath, 
evaporate some of the 
distilled water to dry- 
ness. Carefully regulate 
the heat so that as the 
water evaporates there 
will be less and less heat. 
This is to prevent the 
breaking of the evapo- 
rating dish by too much 
heat at the close. Ex- 
amine the evaporating 
dish. See if there is 
any residue. (2) Evapo- Fig. 29.— Distillation of water, 

rate to dryness a similar amount of ordinary water, and observe 
the residue. 

Questions. (1) Why do the contents of flask A become cloudy 
after boiling and cooling ? (2) Why was the residue obtained \>y 
one test and not by the other ? (3) What became of the residue 
when the water was distilled ? (4) How could you distil water 
on a larger scale for drinking purposes, if necessary to do so? 

60. Physical Properties.— When water cools, it 
reaches its maximum density at 4 C ; below this point, 
it expands, and hence ice has a lower specific gravity 
than water. All natural waters contain more or less im- 
purities in the form of mineral and vegetable matter and 
gases. Pure water can be prepared only by distillation. 
When a substance, as salt, is dissolved in water, a solu- 




58 AGRICULTURAL CHEMISTRY 

tion is obtained. The particles of the material are sepa- 
rated in the process of solution, and every part of the so- 
lution, even though dilute, contains some of the dissolved 
substance. When a substance is dissolved, ions are pro- 
duced. They are small masses of the material that have 
undergone changes due to the action of the solvent. The 
ions possess definite electrical properties. When a sub- 
stance goes into solution, the process is both physical and 
chemical. In some cases a change of temperature occurs, 
as when ammonium nitrate solution is made. 

16. Water of Crystallization. — Many substances con- 
tain, in chemical combination, water necessary for the 
formation of crystals. This is what is meant by water 
of crystallization. Without this water, crystals could 
not be formed. The amount of water required bears a 
definite relation to the composition of the crystals. When 
copper sulfate crystallizes, 7 molecules of water of crys- 
tallization are added to the substance. In purchasing 
some substances, as sulfate of soda, a large amount of 
water is obtained, as this compound contains 10 molecules 
of water of crystallization. When the substance is heated 
in an oven, to a sufficiently high temperature, usually 
above ioo° C, the water of crystallization is expelled and 
the anhydrous substance is obtained. Water of crystal- 
lization is entirely different from hydroscopic moisture or 
moisture which is absorbed from the air. Some chem- 
ical compounds, when exposed to the air, give up their 
water of crystallization. Such substances are called 
efflorescent. Other compounds, as KOH and CaCl 2 , ab- 



WATER 59 

sorb moisture from the air. Such substances are called 
deliquescent. Water takes an important part in chem- 
ical reactions ; in fact, many of the reactions expressed 
in the form of equations could not take place without the 
presence of water. 

62. Natural Waters.— Rain, spring, lake, river, and 
sea waters are some of the principal forms in which water 
is found in nature. Some waters contain a sufficient 
amount of dissolved salts to give them 
definite characteristics. Such are 
known as mineral waters. The most 
common impurities in water are lime, 
magnesia, potash, soda, and iron com- 
pounds. These substances give prop- 
erties to the water which cause them 

Fig". 30. 

to be characterized as hard or soft, Typhoid bacillus, 
according to the nature and amount of minerals dis- 
solved. All natural waters are liable to contamination, 
and the organic impurities of water serve as food for dis- 
ease-producing organisms. The sanitary condition of 
the water supply has an important bearing upon health. 
Typhoid fever, cholera, and other bacterial diseases are 
frequently caused by poor drinking water. The spores 
of the organisms present in the water are taken into the 
body where they rapidly multiply. Surface wells, par- 
ticularly when near barns and dwellings, and in thickly 
settled regions, are frequently in an unsanitary condition. 

63. Impurities in Water. — The nature of the impuri- 
ties in the soil through which water flows determines the 
kinds of impurities in the water. If a soil is polluted 




60 AGRICULTURAL CHEMISTRY 

with decaying animal and vegetable refuse matters, the 
soluble parts of these materials along with the countless 
organisms which they contain, become a part of the 
drinking water. The impurities in well waters are (i) 
organic matter, and (2) mineral salts. When waters are 
charged with excessive amounts of organic matter, the 
solids obtained by evaporating the water to dryness 
blacken when ignited. The carbon compounds in a liter 
of some water will require 20 nigs, or more of oxygen for 
oxidation. The organic matter may decompose and be- 
come harmless, but it is liable, in times of epidemics, to 
furnish food for disease germs. 

A water that is comparatively free from organic matter 
is not nearly so apt to be a source of trouble by conveying 
disease germs as one that contains a large amount of 
organic refuse, as this is the best kind of food for the 
development of germs which cause many of the most fatal 
diseases. Vegetable matter, as a rule, is not as harmful 
in a water as is animal matter. The organic matter that is 
dissolved in waters is constantly decaying ; this decom- 
position is the result of the workings of minute organisms 
known as bacteria, and the disease-producing bacteria may 
be present as well as the harmless kinds. The history of 
the water supply of large cities has shown that a water 
which is comparatively free from organic matter is the 
best for household purposes. The reasons are obvious. 
Excessive amounts of nitrogenous organic matter in 
drinking waters are particularly objectionable, as the 
source of this material is often sewage or surface drain- 
age, as from a swamp. 



WATER 



6l 



Deep well waters are less liable to be contaminated with 
organic impurities than surface wells, but a deep well is 
not above suspicion because the layers of soil are subject 
to changes in slope, and the water from a deep well may- 




Fig. 31 — Well contaminated with drainage from swamp. 

receive surface drainage from some distant place, as indi- 
cated in the illustration (Fig. 31). Although the soil 
would remove a portion of the impurities and the organic 
matter would be partially oxidized, the water would not 
be entirely free from contamination. 

64. Location of Wells. — The well should be remote 
from barns and cesspools. Large trees about wells are 
objectionable because the water is fouled by waste matter 
thrown off by the roots. The top of the well for 6 or 8 
feet should be laid with cement. The well platform 
should be tight so that small animals are kept out. 
Drain water from the spout should be carried away from 
the well platform and the watering trough should not be 
directly over the well. The land should slope away from 
the well and the surfacing should be of clay. The well 
should have ventilation, and should occasionally receive 
a cleaning. 

65. Mineral Impurities.— Calcium carbonate, calcium 



62 



AGRICULTURAL CHEMISTRY 



sulfate, sodium chlorid, and sodium sulfate are the most 
common minerals present in water. In alkali waters the 




Fig. 32.— Construction of well. 

mineral impurities consist of large amounts of sodium or 
potassium compounds, and there is no way of improving 



WATER 



63 




r^?<~~^ CHARCOAL \Jj / 



such waters except by distillation. Different kinds of 
mineral matter, if present in excessive amounts, may im- 
part medicinal properties ; magnesium sulfate (Epsom 
salts) acts as a purgative, 
while calcium sulfate causes 
costiveness. Strong alkaline 
waters can generally be de- 
tected by their salty taste. 

The presence of a large 
amount of limestone in waters 
is not so serious as the pres- 
ence of other minerals. Waters 
sometimes contain limestone 
to such an extent that when 
boiled they become cloudy, 
which is because of the re- 
moval of the carbonic acid 
gas ; this caused the limestone to remain in solution. 
Waters that contain limestone are not generally consid- 
ered injurious to health although they 
are not so satisfactory for cleaning pur- 
poses on account of the lime acting upon 
the soap and forming a scum of insoluble 
lime soap. A large amount of lime- 
stone, gypsum, etc., is what causes waters 
to be hard. Some waters contain iron 
compounds, as carbonate of iron which, 
upon contact with the air, forms hydrate 
•of iron, and is deposited as a brownish red sediment. 
Some waters contain so much mineral matter that when 




Fig. 33. — Charcoal water filter. 






^Ullife 



Fig. 34— Unglazed 
porcelain filter. 



6 4 



AGRICULTURAL CHEMISTRY 



used for generating steam they produce a large amount of 
boiler scale. This can be partially prevented by the use 
of materials containing tannic acid. 

66. Methods of Improving Drinking Waters. — (i) 

By boiling, which destroys disease-producing organisms. 
Boiled or sterilized water, however, is not free from the 

poisonous compounds 
which many organisms 
produce. In cases of 
pestilential diseases, 
water should always be 
boiled. 

(2) By filtering 
through charcoal or 
through disks of un- 
glazed porcelain-like 
material, which results 
in removing a large part 
of the organic matter. 
Special care, however, 
should be taken to keep 
the filter clean, other- 
wise it will be a source 
of contamination. Boil- 

— ■■ — ing the water before fil- 

Fi g . 35.-Pasteur water filter. tering also improves its 

sanitary condition. One of the most effectual forms of 
water filters is the Pasteur filter, in which the water 
passes through a series of tubes which present a large sur- 
face area for filtering. 




WATER 65 

(3) By distilling, which removes all mineral impurities, 
and the water is also purified from organic matter. It is 
the most effectual way of removing all kinds of impurities 
and rendering the water free from organisms, and safe for 
use. 



CHAPTER IX 
Air 

67. Air a flechanical flixture. — Air is a mechanical 
mixture composed of a number of gases and compounds 
in about the following proportions : (1) nitrogen, 79 per 
cent.; (2) oxygen, 20 per cent.; (3) carbon dioxid, 0.04 
per cent.; (4) ammonium compounds in small amounts ; 
(5) moisture; (6) ozone; (7) hydrogen peroxid ; (8) 
argon ; (9) dust : organic matter, and micro-organisms. 
That air is a mechanical mixture is shown by its not hav- 
ing a constant chemical composition, which is necessary 
for all compounds, and when nitrogen and oxygen are 
mixed, in the same proportion as in air, there is no evi- 
dence of a chemical reaction, as change of volume or 
temperature. The air that is dissolved in water is of 
different composition from atmospheric air, due to the fact 
that oxygen is more soluble in water than is nitrogen. 
The occurrence of nitrogen and oxygen in the air, and 
the chemical and physical properties of these gases have 
been discussed in Chapters IV and V. 

68. Carbon Dioxid. — The amount of carbon dioxid in 
the air is small, about 0.04 per cent., and it is supposed 
to remain fairly constant in amount. It is produced 
from : (1) combustion of carbon-containing materials, as 
fuels ; (2) decaying of organic matter ; and (3) respira- 
tion of animals. The carbon dioxid of the air serves as 
food for plants and is used for the construction of plant 
tissue. The amount produced and that used by vegeta- 



AIR 67 

tion nearly balance each other, so that the carbon dioxid 
in the air remains fairly constant. While the percentage 
amount in the air is small, the total amount is quite 
large ; it is estimated that over each acre of the earth's 
surface, there are about 30 tons of carbon dioxid at the 
disposal of plant bodies. Carbon dioxid itself is not 
such a poisonous gas, but it is usually associated in 




Fig. 36. — Ventilating board in window for obtaining fresh air. 

respired air with noxious and poisonous products thrown 
off by the lungs. Hence the amount in a room is taken 
as the index of the completeness of ventilation. When- 
ever the carbon dioxid in a room exceeds 0.1 per 
cent., the poisonous products associated with it are 



68 AGRICULTURAL CHEMISTRY 

considered to be too large in amount for perfect sanitary- 
conditions. While carbon dioxid is a product of respira- 
tion, and is of no direct economic importance to animals, 
it is indirectly of great importance because of its serving 
as food for plant bodies. It is a heavy gas, but in a room 
it diffuses and is quite evenly distributed. Its presence 
in pure and in respired air can be shown by the following 
experiment : 

Experiment g. — Pour 10 cc. of lime water (calcium hydrate) 
into a test-tube, and blow through it, using for the purpose a clean 
glass tube. Observe the precipitate of calcium carbonate. Expose 
about 10 cc. of lime water in a beaker for twenty-four hours, and 
observe the result. The reaction which takes place between the 
lime water and the carbon dioxid of the air is as follows : 
Ca(OH) 2 + C0 2 = CaC0 3 + H 2 0. 

Questions, (i) What caused the precipitate to form? (2) What 
was produced? (3) Is CaCO s soluble in water? (4) How do you 
determine whether or not a gas is C0 2 ? (5) How does the product 
from this experiment compare with that from the burning candle? 

In the ventilation of dwellings, barns and stables, it is necessary 
that the products of respiration be removed as completely as possi- 
ble and not allowed to accumulate and endanger health. Pure air 
is as important as pure food or water. Impure air is frequently the 
cause of disease and indirectly it may, by lowering the vitality of 
the individual, prepare the way for disease. When gasoline or 
kerosene is used as fuel, more thorough ventilation is necessary 
than when wood or coal is used, because the products of combus- 
tion from the gasoline and kerosene are given off into the room 
instead of being carried out through the chimney. The subject of ' 
ventilation, which forms a part of sanitary chemistry, is, as a rule, 
given too little attention. 

60. Ammonium Compounds. — When nitrogenous or- 
ganic compounds decay, ammonia gas, NH 3 , is given off. 



AIR 



6 9 



Since nitrogenous animal and vegetable matters are con- 
stantly undergoing decay, some ammonia is always pres- 
ent in the air. The ammonia gas unites with the carbon 
dioxid and forms ammonium carbonate. In barns and 
stables, where the ventilation 
is poor, abnormal amounts of 
carbon dioxid and ammonia 
are formed from the respiration 
and waste products of animals. 
When carbon dioxid forms to 
such an extent that it produces 
a white coating upon stones 
and boards, it shows enough 
ammonium carbonate to be in- 
jurious to animals. Nitrogen, 
in traces, in the form of ammo- 
nium nitrate and nitrite, is 
also present in the air. The 
amount of combined nitroge- 
nous compounds in the air is 
small and is not sufficient to 
furnish food for plants. 

70. rioisture. — The amount 
of moisture in the air ranges 
between wide limits, from com- 
plete saturation to desert conditions. When the air con- 
tains all the moisture it can hold, it is said to be saturated. 
Under ordinary conditions, the humidity, or per cent, of 
saturation ranges between 60 and 85. The amount of 
moisture in the air has an'Jmfluence upon plant growth, 




Fig. 37. — Ventilating flue in chim- 
ney for removing foul air. 



70 AGRICULTURAL CHEMISTRY 

rather because it modifies the conditions of the at- 
mosphere than because it furnishes moisture directly for 
plant growth. The humidity of the air also influences 
many farm operations, as the curing of cheese, which is 
best effected in an atmosphere containing about 85 per 
cent, of moisture. 

71. Ozone and Hydrogen Peroxid. — These are oxidi- 
zing agents, present in the air only in traces. Ozone is 
a modified or allotropic form of oxygen. It is more 
active than ordinary oxygen. Hydrogen peroxid (H 2 2 ) 
readily gives up one of its atoms of oxygen for oxidation 
purposes. H 2 2 = H 2 + 0. 

72. Argon and Helium are elements which are present 
in the air in small amounts. Argon makes up about 1 
per cent, of the volume of the air, and is like nitro- 
gen in many of its chemical characteristics, but is even 
more inactive and inert than nitrogen ; it is the most in- 
active element known. Argon is not supposed to take 
any direct part in animal or plant life. 

73. Organic Impurities.— The amount of dust, dirt, 
and impurities in the air varies with the conditions, as 
rainfall, local influences, and sources of contamination. 
Fine particles of dust, containing decaying vegetable mat- 
ter, are carried long distances by the wind. This decay- 
ing vegetable matter often contains spores of disease 
germs. The dust and impurities in the air can be ob- 
served when a beam of sunlight finds its way into a room; 
then the particles of dust will be seen floating in the air. 
When the air in a room is not in motion, the dust parti- 



AIR 71 

cles separate and settle very much as fine clay separates 
from water which is not disturbed. There are many 
different kinds of organic impurities present in the air. 
The most objectionable of these are decayed refuse mat- 
ters, particularly of animal origin. The air which passes 
over swampy, undrained land, is contaminated with im- 
purities. 

74. Air as a Source of Food. — In both animal and 
plant life, air plays an important role. It contains oxy- 
gen necessary for the existence of animals and carbon 
dioxid essential as food for plants. Over 90 per cent, of 
the total food of our agricultural and useful plants is ob- 
tained from the air as carbon dioxid, or from rain which 
finds its way into the soil. Food which is oxidized in 
the body requires oxygen for combustion. Hence it will 
be seen that the air is the source of the larger portion of 
the total food of both plants and animals. 



CHAPTER X 
Acids, Bases, Salts, and Neutralization 

75. Classification of Elements. — Elements are divided 
into two classes: (1) Acid-forming elements and (2) 
base-forming elements. This division is made according 
to the properties of the elements. 

The basic elements are commonly called metals : iron, 
copper, silver, and lead are examples. The basic elements 
form, with H and O, bases or hydroxids, as KOH and 
NaOH. A base is a compound composed of a metal in 
combination with OH, the hydroxyl radical. This radical 
can be replaced by an acid-forming element. 

An acid is a compound containing hydrogen which 
can be replaced by a metal. In the preparation of hydro- 
gen, the H of HC1 was replaced with zinc. The acid-form- 
ing elements, with hydrogen, and with H and O, form 
acids. 

Bases and acids are opposite in character and proper- 
ties. Acids color blue litmus red, bases color red litmus 
blue. For purposes of study, the different acid- and base- 
forming elements are subdivided into families and groups 
which have definite relationships and common character- 
istics. 

76. Salts. — When an acid and a base are brought to- 
gether, a chemical reaction takes place known as neu- 
tralization. The product formed by the reaction is a 
salt. A salt is a compound formed by the union of acid- 



ACIDS, BASES, SALTS, AND NEUTRALIZATION 73 

and base-forming elements. Salts are neutral compounds. 
In the study of acids, bases, and salts, the character of 
the compound can always be determined from the formula 
as Ca(OH) 2 . Calcium hydrate is a base because it con- 
tains the hydroxyl radical OH. CaCl 2 is a salt because 
it is composed of the acid-forming element CI and the 
base-forming element Ca. HC1 is an acid because it is 
composed of hydrogen and the acid-forming element CI 
and the H can be replaced by a metal. Acids and bases 
do not exist as such to any appreciable extent in nature. 
Salts are neutral compounds and the materials most ex- 
tensively found. In the table, Section 15, the character- 
istic properties of some of the elements as acid- or base- 
forming, are given. A few elements, as will be discussed 
later, have both acid and basic characteristics. 

77. Radicals. — A radical is a group of elements which 
enters into chemical combination like a single element. 
When three elements combine to form a compound the 
combination is made in the following way : Two of the 
elements first form a radical, and then this radical com- 
bines with the third element. Every radical has its own 
valence which is independent of that of its separate atoms. 
A radical can exist only in chemical combination ; it can- 
not be separated. Its individuality as a radical exists 
only when in combination. The elements which unite 
to form a radical do not do so according to the law of 
valence. There are only a few of the more common 
radicals which require special study at this stage of the 
work. Example : When H, S, andO combine, the S and 
O first form a radical, S0 2 , which has a valence of 2. Two 



74 AGRICULTURAL CHEMISTRY 

atoms of H combine with one S0 4 radical and form H 2 S0 4 . 
Some of the more common radicals are : 



Radi- 
cal. 

co 3 

C10 3 
N0 3 

po 4 

NH 4 


Valence. 
2 
I 
I 

3 
1 
1 
2 
1 
2 
2 


Compounds formed 
with H. 

Carbonic acid 

Chloric acid 

Nitric acid 

Phosphoric acid 


Compounds formed 
with metals. 

Carbonates 

Chlorates 

Nitrates 

Phosphates 

Ammonium compounds 

Hydroxids 

Silicates 

Nitrites 

Sulfites 

Sulfates 


OH 

Si0 3 
N0 2 
S0 3 

so 4 


Water 
Silicic acid 
Nitrous acid 
Sulfurous acid 
Sulfuric acid 



78. Naming of Acids. — Acids are named according to 
the characteristic acid element or radical present, as sul- 
furic acid, H 2 S0 4 , in which S is the characteristic acid 
element. The most common acids have the ending ic. 
Some acids have an ous ending, as H 2 S0 3 , sulfurous 
acid. The acid which has the smaller amount of oxygen 
has the ending ous, while the acid which has the larger 
amount of oxygen has the ending ic. 

Name the following acids : HN0 3 , HN0 2 , H 2 S0 4 , 
H 2 S0 3 , H 3 P0 4 , H 3 P0 3 , H 3 As0 4 , H 3 As0 3 . 

79. Naming of Bases. — Bases are named according to 
the characteristic base element which they contain. All 
bases are called hydroxids, as calcium hydroxid, Ca(OH) 2 , 
and potassium hydroxid, KOH. 

The rule in regard to the endings ic and ous applies in 
the case of bases as well as in that of acids; that is, when 
an element forms two hydroxids, the ending ic is applied 



ACIDS, BASES, SAI/TS, AND NEUTRALIZATION 75 

to the one with the larger amount of hydroxyl, and the 
ending ous to the one with the smaller amount. 

Name the following bases: Mg(OH) 2 , NH 4 OH, NaOH, 
Fe(OH) 2 , Fe(OH) 3 , Al(OH)„ CuOH, Cu(OH) 2 . 

80. Naming of Salts. — Salts are named according to 
the acid and base elements which they contain, as K 2 S0 4 , 
potassium sulfate, composed of potassium, K, and the 
sulfate radical, S0 4 . Most salts have an ending ate. 
A few have an ending ite. The salts derived from the 
acids with the ic ending always have the ate ending, as 
sulfuric acid, which always produces sulfates, phos- 
phoric acid, phosphates, and nitric acid, nitrates. The 
acids ending with ous produce salts which end in 
ite, as nitrous acid always produces nitrites, and sul- 
furous acid, sulfites. Salts that are composed of only 
two elements always have an ending of id, as sodium 
chlorid, NaCl, and sodium sulfid, Na 2 S. 

81. Double Salts. — A double salt is one that is com- 
posed of two base elements in combination with one acid 
radical, as NaKS0 4 , sodium potassium sulfate. Double 
salts are formed from acids which contain two replaceable 
hydrogen atoms, as H 2 S0 4 , by replacing one of the H 
atoms with one base element and the remaining H atom 
with another base element. This is represented graphi- 
cally as follows : 

H v Na v 

H 2 SO, = >S0 4 = >S0 4 . 
H' K / 

82. Acid Salts. — An acid salt is one in which only a 
part of the H of the acid has been replaced. An acid 



76 AGRICULTURAL CHEMISTRY 

salt always contains H, a metal, and a radical. HNaS0 4 
is acid sodium sulfate, as only one H atom has been 
replaced with Na. A normal salt contains no replace- 
able H. 

83. Basicity of Acids. — Acids with one replaceable H 
atom are called monobasic acids, as HC1 and HN0 3 . 
Acids with two H atoms are dibasic, as H 2 S0 4 , H 2 Si0 3 , 
and H 2 C0 3 . When an acid contains three replaceable H 
atoms, it is tribasic, as H 3 P0 4 . 

84. Two Series of Salts. — When a base element has 
more than one valence, it forms two series of salts. For 
example, Fe has a valence of 2 and 3. The first series 
of salts is known by the ending ous. The second series 
has an ic ending. The one ending means that the com- 
pound is formed from the lower valence of the element, 
as FeCl 2 , ferrous chlorid, while FeCl 3 is called ferric 
chlorid. There are two series of copper salts ; CuCl is 
called cuprous chlorid, and CuCl 2 , cupric chlorid. 

Name the following salts : FeCl.„ FeCl 3 , FeS0 4 , 
Fe 2 (S0 4 ) 3 , Fe(N0 3 ) 2 , Fe(N0 3 ) 3 , Fe(OH) 2 , Fe(OH) 3 , 
HgCl, HgCl 2 , SnCl 2 , SnCl„ MnCl 4 , MnCl 2 . 

Experiment 10. — Neutralization and preparation of salts. 
Obtain two burettes from the instructor for these experiments. 
Measure out 5 cc. of concentrated HC1 and 95 cc. of water ; 
after mixing, fill one of the burettes with this diluted HC1 (Fig. 
38). Use your funnel for filling the burette, and then carefully 
wash the funnel. Prepare a dilute solution of NH 4 OH, using 90 
cc. of water and 10 cc. of the shelf NH 4 OH. After mixing, fill the 
second burette with this preparation of diluted NH 4 OH. Before 
using the solution in the burette, it should be lowered to the zero- 
point by carefully opening the pinch-cock. Always allow the tip 



ACIDS, BASES, SALTS, AND NEUTRALIZATION 77 



from the burette exactly 20 



of the burette to be filled with the solution before beginning the 
experiment. 

Into a small beaker, measure 
cc. NH 4 OH, with 10 or 12 drops 
of cochineal solution, which is 
changed to a deep purplish color 
by the alkali ; then slowly add HC1 
from the other burette, constantly 
stirring the solution in the beaker 
until a decided change in color is 
observed. When all of the NH 4 OH 
has been neutralized, the solution 
has a yellowish red color. Note the 
number of cubic centimeters of 
HC1 used for neutralizing the 20 cc. 
of NH,OH solution. Add a drop 
or two from the NH 4 OH burette 
and note if there is a change of 
color. When the solution is neu- 
tralized, one or two drops of HC1 
or NH^OH should give a decided 
change of color. If too much acid 
has been used, add a measured 
amount from the NH 4 OH burette 
until the solution is neutralized. 
Finally note the total quantity of 
HC1 and NH 4 OH used. Repeat this 
experiment, using 20 cc. of the 
HC1 solution. 

Questions. ( 1 ) What was formed 
when the HC1 neutralized the 
NH 4 OH solution? (2) Write the 
reaction. (3) What would be the 
result if the neutralized solutions Fig - 2 ' - Burette - 

were evaporated to dryness ? (4) Calculate the amount of HC1 re- 
quired to neutralize 1 cc. of NH 4 OH. 




78 AGRICULTURAL CHEMISTRY 

Experiment II. — Neutralization. Repeat Experiment 10, using 
dilute H 2 S0 4 and NaOH solutions that have been prepared for this 
experiment. After completing the experiment, clean the burettes 
thoroughly and return them to the instructor. 

Questions, (i) What was formed when H 2 S0 4 neutralized 
NaOH? (2) Write the chemical reaction. (3) What was formed 
as the products of this reaction? (4) How can the salt product be 
obtained? (5) In writing the reaction, why do we use 2NaOH in- 
stead of NaOH? (6) How does the product of Experiment 10 
differ from the product of Experiment it? (7) What other 
acids could be used for neutralizing NaOH and NH 4 OH ? (8) What 
other bases could be used for neutralizing HC1 and H 2 S0 4 ? 
(9) What is an acid ? (10) What is abase? (11) What is a salt? 
(12) Which do we find most abundantly in nature, acids, bases, or 
salts? Why? 

Experiment 12. — Preparation of a salt. Put 10 cc. dilute 
HC1 and 10 cc. water into the evaporator. Measure out 10 cc. of 
NaOH into a beaker and add 50 cc. water. Add this diluted NaOH 
to the evaporator a little at a time until the solution is neutral to 
litmus paper. Do not dip the paper into the solution, but transfer 
a drop by means of a glass rod from the evap- 
orator to the paper. In case too much NaOH 
has been used, add a drop or two of the acid. 
Bases or alkalies turn red litmus paper blue, 
while acids turn blue litmus paper red. When 
Pig. 39.— sodium chlorid the solution is neutral, it has no perceptible 
crystals (common salt). act i n upon litmus paper. Place the evap- 
orating di6h upon the sand-bath, and apply heat until the solution 
is evaporated to dryness. Carefully regulate the flame so as to 
avoid excessive heating. This will prevent spattering when the 
solution becomes concentrated. 

Questions. (1) What is left in the evaporator ? (2) From what 
was it produced? (3) Write the chemical reaction. (4) Taste 
some of the material in the evaporating dish. How is it possible for 
this material to be formed from two such unlike compounds as HC1 




ACIDS, BASES, SALTS, AND NEUTRALIZATION 79 

andNaOH? (5) What is neutralization ? (6; Are definite amounts 
by weight of HC1 and NaOH required for neutralization ? (7) How 
many molecules of HC1 are required to neutralize one of NaOH ? 
(8) How much does a molecule of HC1 weigh? (9) Of NaOH? 
(10) How many parts by weight of each must be taken for neu- 
tralization ? (11) How does this illustrate the law of definite pro- 
portion ? 



CHAPTER XI 
Hydrochloric Acid, Chlorin, and Chlorids 

85. Occurrence. — The element chlorin is never found 
in a free state in nature, but is always in combination 
with other elements, as with sodium, forming sodium 
chlorid. With hydrogen, chlorin forms hydrochloric 
acid. 

86. Preparation. — Hydrochloric acid is produced by 
the action of H 2 S0 4 on NaCl, the reaction being 
2 NaCl + H 2 S0 4 = Na 2 S0 4 + 2HCI. Heat is applied 
and the hydrochloric acid gas is expelled and col- 
lected in water. In the preparation of hydrochloric acid, 
the CI part of the compound is supplied by the NaCl, while 
the sulfuric acid furnishes the hydrogen. Hydrochloric 
acid can also be made by direct union of the elements 
hydrogen and chlorin. It is prepared in the laboratory 
in the following way : 

Experiment 13. — Preparation of hydrochloric acid. Arrange 
the apparatus as shown in Fig. 40. A sand-bath, containing 
sand, is placed upon either the tripod or the large ring of the iron 
ring-stand. Tube B connects flask A with Woulff bottle C, which 
contains 100 cc. of water. The tube is made from a piece of glass 
tubing 22 to 24 inches long, with one right-angled bend about 3 
inches from the end, and another, parallel and about 6 inches from 
the first bend. This tube is connected with both flask A and the 
Woulff bottle by means of tight-fitting corks. Tube B passes into 
the bottle but not below the surface of the liquid. Through a tight- 
fitting cork in the middle neck of Woulff bottle C passes a safety 
tube so adjusted that it dips just below the surface of the water in 
C. This safety-tube is a straight piece of glass tubing, 9 or 10 



HYDROCHLORIC ACID, CHLORIN, AND CHLORIDS 8 1 



inches long. Woulff bottle C is connected with a second Woulff 
bottle by means of a bent tube which passes below the water in the 
second bottle but is above 
the water in the first bot- 
tle. The apparatus, as 
constructed, allows the 
gas which is generated in 
flask A to pass through 
into C and saturate the 
water. Some of the acid 
passes over into the sec- 
ond Woulff bottle. Since 
the delivery tubes in C do 
not pass below the surface 
of the liquid, and the 
pressure is equalized, no 
liquid can be drawn back 
into flask A. 

Place 15 grams sodium 
chlorid (NaCl, common 
salt) and 30 cc. of concen- 
trated H 3 S0 4 in flask A. 
Apply heat to the flask, 
and after ten minutes re- 
move the burner and test Fi g- 40.— Preparation of hydrochloric acid, 
the liquid in both Woulff bottles with litmus paper. Then make 
the following tests : 

( 1 ) Disconnect the delivery tube and test the escaping gas with 
wet litmus paper. (2) Collect a little of the gas in a test-tube, and 
test it with a burning splinter. (3) Put 2 or 3 cc. of silver nitrate 
(AgN0 3 ) into a test-tube and then a like amount of HC1 from the 
first Woulff bottle. Observe the result. (4) Leave the test-tube and 
contents exposed to strong sunlight for a few minutes. (5) Put a 
small piece of zinc into a test-tube and cover it with some of the 
acid from the first Woulff bottle. Observe the result. 

Questions. ( 1 ) What chemical reaction took place when H 2 S0 4 

6 




82 AGRICULTURAL CHEMISTRY 

and NaCl were brought together? (2) Is HC1 a solid, liquid, or 
gas? Why? (3) Color? (4) Is it soluble in water ? Why? (5) 
What was formed when the HC1 was added to the test-tube con- 
taining AgN0 3 ? Give the reaction. (6) Is HC1 combustible or a 
supporter of combustion? (7) What is a chlorid ? (8) What 
effect would HC1 gas have upon plants ? 

87. Properties. — Hydrochloric acid is a colorless gas, 
soluble in water. When exposed to the air, it combines 
with the moisture of the air. The concentrated acid 
used in the laboratory is a solution of about 40 per cent. 
HC1. Chemically, HC1 is an active acid, and is neither 
combustible nor a supporter of combustion. When it 
neutralizes bases, chlorids are always formed. Hydro- 
chloric acid is distinguished from other acids by its reac- 
tion with silver nitrate, a white precipitate of silver 
chlorid being produced which is soluble in ammonia and 
is blackened in sunlight. Hydrochloric acid is used 
extensively in the laboratory in the preparation of vari- 
ous compounds, and for the production of chlorin. 

88. Preparation of Chlorin. — Chlorin is prepared by 
the action of an oxidizing agent, as manganese dioxid, 
upon hydrochloric acid, manganese chlorid, water, and 
chlorin gas being formed as products. The reaction is 
Mn0 2 + 4HCI = MnCl 2 + 2H 2 + 2CI. In this reaction 
the valence of manganese is changed from 4 to 2, and as 
a result free chlorin gas is liberated. The method of 
preparation in the laboratory is as follows : 

Experiment 14. — Preparation of chlorin. It is preferable 
to set up the apparatus for generating chlorin under one of the 
hoods. Arrange the apparatus as shown in Fig. 41. Place 10 
grams of Mn0 2 and 15 or 20 cc. of HC1 in flask A. By means of 



HYDROCHLORIC ACID, CHLORIN, AND CHLORIDS 83 



the delivery tube B, and a tight-fitting cork, the CI gas, when 

generated, passes into the large cylinder, in which has been placed 

a green leaf, a piece of colored cloth, and paper upon which is 

some writing. The delivery tube passes through the hole in the 

ground-glass plate, without any cork. To generate the chlorin, 

apply gentle heat to the flask, and 

as soon as the cylinder is nearly 

filled with the CI gas, which can be 

observed by its color, remove the 

flame so as to prevent any of the 

gas from escaping into the room. 

Do not inhale any of the fumes, as 

they are irritating to the throat and 

lungs. Make the following tests : 

( 1 ) Observe the effect which the 
chlorin gas has upon the cloth, 
paper, and leaf. (2) To the cylin- 
der, add 5 cc. water containing two 
or three drops of indigo solution. 
Observe the result. 

Questions. ( 1 ) Give the physical 
properties of CI gas, odor, weight, 
and color. (2) What caused the 
liberation of the CI gas from the 
HC1? (3) Write the reaction. (4) 
What are some of the chemical 
properties of chlorin as observed 
from the changes which have taken place in the materials in the 
cylinder? (5) What is a chlorid ? (6) Name five compounds con- 
taining chlorin. (7) Why is CI gas employed as a disinfectant? 
Explain its action as a disinfectant. (8) What is bleaching-powder, 
and how is it used as a disinfectant? (9) NaCl is necessary for 
animal life ; CI is one of the elements of the compound ; CI is de- 
structive to animal life ; why can you not conclude that NaCl con- 
taining CI is destructive to animal life? 




Fig. 41. — Preparation of chlorin. 



84 AGRICULTURAL CHEMISTRY 

89. Properties. — Physically considered, chlorin is a 
heavy, greenish yellow gas, with a penetrating, suffo- 
cating odor. Chlorin gas is poisonous. Chemically, it 
is an active element and has strong affinity for nearly all 
other elements. It readily combines with metals, form- 
ing chlorids, and light and heat are evolved during the 
reaction. Chlorin is an active bleaching reagent, as it 
changes the composition of vegetable dyes, thus destroy- 
ing their color. Bleaching-powder is a mixture of cal- 
cium hypochlorite and calcium chlorid, and when used 
chlorin is liberated. Chlorin is also used as a disinfectant 
and as a germicide, for it is destructive to life, particu- 
larly to the lower forms. It is used extensively for both 
bleaching and disinfecting purposes. Chlorin takes no 
part directly in life processes, although its compounds, 
particularly sodium chlorid, are necessary as mineral food 
for animals. 

90. The Chlorin Group of Elements — Fluorin, chlo- 
rin, bromin, and iodin form a natural group of elements, 
known as the chlorin family. These elements are all 
closely related. They form similar acids with H, and 
similar salts with the metals. Some of the most im- 
portant relationships and points of difference between 
members of the chlorin family will be observed from the 
following table : 

Physical 
Element. At. wt. conditions. H compound. Na compound 

Fluorin 19 Light gas HF1 NaFl 

Chlorin 35-45 Heavy gas HC1 NaCl 

Bromin 79-95 Liquid HBr NaBr 

Iodin 126.85 Solid HI Nal 



HYDROCHLORIC ACID, CHLORIN, AND CHLORIDS 85 

91. Chlorids. — Combined with the metals, chlorin forms 
chlorids. As a class, the chlorids are quite stable com- 
pounds, inasmuch as chlorin has strong affinity for nearly 
all of the metals. The properties of the different chlorids 
vary with the metal with which the chlorin is combined. 
The chlorids do not take such a direct part in plant as in 
animal nutrition. When present in either soil or water 
in any appreciable amount, the soil is sterile and the 
water is not suitable for either drinking or irrigation 
purposes. Sodium chlorid is found in nature most 
abundantly of any of the chlorids. 

Problem 1. — How much H 2 S0 4 is required to combine with 2000 
pounds NaCl in making HC1 ? 

Problem 2. — How much HC1 can be made from 2000 pounds of 
NaCl? 

Problem 3. — How much Na 2 S0 4 is produced when 2000 pounds 
NaCl are used for making HC1 ? 



CHAPTER XII 
Nitric Acid and Nitrogen Compounds 

92. Occurrence. — Nitric acid does not occur in nature 
in a free state, but nitrates or salts of nitric acid are found 
as natural products. Since all normal nitrates are soluble 
in water, they are never found in great abundance in 
soils. In regions of scant rainfall, where climatic con- 
ditions have been favorable for the formation of nitrates, 
deposits of nitrate of soda are occasionally found. The 
nitrifying organisms of the soil, when supplied with 
food, moisture, suitable temperature, and other requisite 
conditions, produce nitrates which are utilized as food 
by plants. The process of nitrification which takes place 
in the soil, results in changing the inert and unavailable 
nitrogen to a soluble and available condition. 

93. Preparation. — The same principle is applied in the 
preparation of nitric acid as in the preparation of hydro- 
chloric acid. It is produced by the action of H 2 S0 4 upon 
a salt ; when a chlorid is used, hydrochloric acid is the 
product, and when a nitrate is used nitric acid is the 
product. The reaction when sodium nitrate is used is : 
2 NaN0 3 + H 2 S0 4 = Na 2 S0 4 + 2HNO3. 

Experiment 15. — Preparation of nitric acid. Special care 
should be exercised by the student in the preparation of nitric acid, < 
because if any is spilled on the hands it causes painful burns and 
wounds that are difficult to heal. Provided the student is careful 
and follows the directions given, there is no danger whatever in 
the preparation of this material. x\rrange the apparatus as shown 
in Fig. 42. The delivery tube used in the preparation of NH 3 may 



NITRIC ACID AND NITROGEN COMPOUNDS 



87 



be used for this experiment. If necessary, a brick or block may 
be placed under the cylinder. The delivery tube should pass into 
and nearly to the bottom of a test-tube which is immersed in cold 
water in the cylinder. Put 15 cc. concen- 
trated sulfuric acid (H 2 S0 4 ) and 10 
grams of either sodium nitrate (NaN0 3 ) 
or potassium nitrate (KN0 3 ) into the 
flask and apply heat until about 4 or 5 cc. 
of HN0 3 is distilled and collected in the 
test-tube. Do not remove the flame un- 
less the end of the delivery tube is above 
the liquid in the test-tube, otherwise the 
liquid will be drawn back into the flask. 

Make the following tests with HN0 3 . 
( 1 ) Remove a drop of the acid by means 
of a glass tube, and apply it to either a 
piece of woolen cloth or silk. Observe 
the result. (2) Place a few drops of indigo 
solution in a test-tube containing 5 cc. of 
water, then add about 2 cc. of HNO s . Ob- 
serve the result. (3) Place a small piece 
of copper in the test-tube containing the 
remainder of the acid. Observe the result. 
If no reaction takes place, add a little 
water. Do not pour the contents of the 
flask into the sink or waste jars until 
cool, otherwise the hot acid coming in contact with cold water 
may cause spattering of the acid. 

Questions. ( 1 ) Why was HjSO^ used in the preparation of this 
compound? (2) What material supplied the N0 3 radical? (3) 
Write the reaction which took place in the flask after heat was ap- 
plied. (4) Is HN0 3 a solid, liquid, orgas? Why? (5) What caused 
the red fumes to be given off when the copper was added to the 
test-tube ? (6) Does HN0 3 give off H when a metal is added to it ? 
Why? (7) Why did the HN0 3 bleach the indigo solution? (8) 
Why is ordinary HN0 3 colored yellow? (9) Is HN0 3 an active or 
inert chemical ? (10) What is a nitrate? 




Fig. 42. — Preparation of 
nitric acid. 



88 AGRICULTURAL CHEMISTRY 

94. Properties.— When pure, nitric acid is a colorless 
liquid; the commercial acid has a yellow color because 
of the presence of oxids of nitrogen. Nitric acid is an 
active oxidizing reagent, and when metals, as copper and 
iron, are dissolved in it, brown fumes of N0 2 are given 
off because the hydrogen, as soon as liberated, is oxidized 
by the excess of acid and N0 2 is formed. H + HN0 3 = 
H 2 + N0 2 . Nitric acid imparts a permanent yellow 
color to wool, silk, and all albuminous matter. 

95. Importance. — In the laboratory, nitric acid is used 
as an oxidizing agent. It is used commercially in the 
dyeing of cloth, although it has a tendency to weaken the 
wool fibers. Salts of nitric acid are important because 
they are of so much value as plant food, and particularly 
in the manufacture of commercial fertilizer, where it sup- 
plies nitrogen. Potassium nitrate is used in the manu- 
facture of gunpowder. Nitrates are of great importance 
in agriculture. 

Ammonia 

96. Occurrence. — Ammonium compounds are present 
in small amounts in the air, rain water, and in the soil, 
and are produced from decaying nitrogenous organic 
matter. The chief source of the ammonia which serves 
as the basis for the preparation of ammonium salts is 
the ammonia water obtained in the process of purifying 
illuminating gas made from soft coal. The nitrogen 
compounds of the coal form ammonia gas, NH 3 , during 
the destructive distillation process. 

97. Preparation. — In the laboratory, ammonia is usu- 



AMMONIA 89 

ally prepared from ammonium- chlorid by treatment with 
a strong base, as Ca(OH) 2 . The reaction is : 

2 NH 4 C1 + Ca(OH) 2 = CaCl 2 + 2NH 4 OH. 

Experiment 16. — Preparation of ammonia. Arrange appa- 
ratus as directed for the preparation of HC1 (see Fig. 40). Into 
flask A, place 10 grams each of dry ammonium chlorid, NH 4 C1, and 
powdered calcium hydroxid, Ca(OH) 2 , and 25 cc. water. Barium 
hydroxid, Ba(OH) 2 , may be used in place of the Ca( OH ) 2 . When 
properly connected, apply heat to the sand-bath from eight to 
twelve minutes. 

Tests for Ammonia. (1) Test the gas with wet litmus paper. 
Note the result. ( 2 ) Test the water in both Woulff bottles with 
litmus paper, and note the result. (3) In an evaporator place 5 cc. 
HC1 and 10 cc. water. Disconnect the delivery tube from Woulff 
bottle C, and pass some of the fumes of the escaping gas over the 
acid in the evaporator. Avoid inhaling any of the gas. (4) Col- 
lect some of the gas in a test-tube and then place the test-tube in- 
verted in a cylinder about one-third full of water. (5) Adds cc - 
of the NH, solution from either of the Woulff bottles to 5 cc. of a 
solution of alum. Note the result. 

Questions. (1) What material supplied the NH 4 part of the 
NH 4 OH ? (2) What caused the gas to be liberated from these ma- 
terials? (3) What chemical reaction took place in flask A after 
the heat was applied ? (4) Why was water used in the Woulff 
bottle? (5) What did the water and the NH 3 gas form? (6) 
What reaction did the NH 3 gas and the NH 4 OH give with the lit- 
mus paper ? (7) Why was not this gas given off into the room? 

(8) Why was not NH 3 collected over water, like H, N, and O ? 

(9) What caused the water to rise in the test-tube? (10) Why 
have you reason to believe that the NH 4 OH caused a chemical re- 
action when added to the solution of alum ? 

98. Properties. — Ammonia is a colorless non-combus- 
tible pungent gas, which unites with water to form am- 
monium hydroxid, NH 4 OH, a basic compound. It is 



90 AGRICULTURAL CHEMISTRY 

completely soluble in water, from which it is easily liber- 
ated by heat. The gas can be reduced to liquid form by 
cold and pressure. Liquefied ammonia passes back to the 
gaseous condition with removal of the pressure, and in so 
doing, heat is absorbed from surrounding bodies. If this 
heat is absorbed from water, the temperature of the water 
is lowered sufficiently to produce ice. This property of 
liquefied ammonia is taken advantage of for the artificial 
production of ice, and for refrigerating purposes. The 
transportation of perishable food materials has been ren- 
dered possible by this method of refrigeration. 

99. Uses. — In the laboratory, ammonium hydroxid is 
used extensively as a reagent for neutralizing acid solu- 
tions and precipitating insoluble hydroxids. Ammo- 
nium salts, when present in any appreciable amounts, are 
destructive to plants, (NH 4 ) 2 S0 4 being less injurious than 
either NH 4 C1 or (NH 4 ) 2 C0 3 . Hence (NH 4 ) 2 S0 4 can be 
used in limited amounts as a fertilizer. Because of its 
being a volatile alkali, ammonia is valuable as a reagent 
for softening water. 

In small amounts, so as to form very dilute solutions, 
the ammonium compounds serve as food for plants, sup- 
plying them with nitrogen which is used for producing, 
within the plant cells, complex nitrogenous compounds, 
as proteids. Ammonium compounds supply only one 
form of nitrogenous plant food. 

100. Oxids of Nitrogen. — Nitrogen forms five com- 
pounds with oxygen : 

N 2 nitrogen monoxid or nitrous oxid. 
N,0, nitrogen dioxid or nitric oxid. 



AMMONIA 91 

N 2 3 nitrogen trioxid or nitrous anhydrid. 

N 2 4 nitrogen tetroxid. 

N 2 5 nitrogen pentoxid or nitric anhydrid. 

While the oxids of nitrogen do not serve as either plant 
or animal food, they are nevertheless important, and a 
study of these compounds is necessary in order to under- 
stand the subject of nitrogen. 

101. Anhydrids. — An anhydrid is an oxid of an acid 
element, or the product which is left after the elements 
which form water are abstracted from an acid. S0 3 is 
sulfuric anhydrid, and is the product formed by ab- 
stracting H 2 from H 2 SO,. H 2 S0 4 = H 2 + S0 3 . N 2 5 
is nitric anhydrid, derived from two molecules of HN0 3 . 
2HNO3 = H 2 + N 2 5 . 

Derive and name the anhydrids of the following acids: 
2H 3 P0 4 , H 2 C0 3 , H 2 Si0 3 , 2HN0 2 , H 2 SO s . 

102. Law of flultiple Proportion. — When nitrogen 
and oxygen combine, the number of parts of nitrogen in 
the various compounds is constant, namely : 2, or 28 
parts by weight in each compound. The number of 
parts of O is always a multiple of the first combination, 
N 2 ; that is, it is either 2, 3, 4, or 5 times as much in 
the other compounds as in the first one. This is an ex- 
ample of the law of multiple proportion. When two 
elements combine in more than one way, the amount by 
weight of one of the elements remains constant in all the 
combinations, while the amount of the other element is 
always a multiple of the first combination. 

The law of definite proportion holds true for each in- 
dividual compound, while the law of multiple proportion 



92 AGRICULTURAL CHEMISTRY 

applies to the entire series, and is a broader application 
of the law of definite proportion. 

103. Importance of the Nitrogen Compounds. — The 

compounds of nitrogen, particularly nitrates and ammo- 
nium compounds, are of importance in agriculture as they 
serve as food for plants. They are difficult to retain in 
soils because of their solubility and the volatility of 
ammonia. In human and animal foods, the nitrogenous 
compounds are of importance in many ways ; hence, in 
economic agriculture the compounds of nitrogen receive 
special consideration. 

Problem 1. — How many pounds of HN0 3 can be produced from 
100 pounds NaN0 3 ? 

Problem 2. — How much H 2 S0 4 is required when 100 pounds 
HNO3 are made? 

Problem j. — How much NH 4 OH can be produced from 10 pounds 
of NH 4 C1? 

Problem 4.— What per cent, of NH 4 OH is NH 3 ? 



CHAPTER XIII 
Phosphorus and Its Compounds 

104. Occurrence. — Phosphorus is found in nature in 
combination with oxygen and other elements, forming 
phosphates, as Ca 3 (P0 4 ) 2 . It is never found in a free or un- 
combined condition. In soils, it is found in small amounts, 
and in many rocks and minerals, as apatite or phosphate 
rock, it is present in large amounts ; it is also found in the 
ash of plants, and in animal bodies, particularly as a con- 
stituent of bones. 

105. Preparation. — It is prepared from bones, which 
are first freed from organic matter by burning. The 
bone ash is treated with sulfuric acid, producing acid 
phosphates, which, when roasted with charcoal, liberate 
free phosphorus. 

106. Properties. — There are two forms of phosphorus: 
the yellow and the red. Yellow phosphorus is a solid 
which ignites at a low temperature. Red phosphorus is 
an allotropic form of the element produced by heating the 
yellow variety in a sealed tube. Yellow phosphorus 
more readily combines with oxygen than does the red, 
and is kept under water to prevent contact with air. 

107. Oxids of Phosphorus. — When phosphorus is 
burned in a current of oxygen or dry air, phosphorus 
pentoxid, P 2 5 , is obtained. This material is a white 
flocculent mass which readily dissolves in water, forming 
metaphosphoric acid. When phosphorus is burned in a 



94 AGRICULTURAL CHEMISTRY 

limited amount of air, it forms phosphorus trioxid, P 2 3 , 
which after long standing dissolves in water, forming 
phosphorous acid. In fertilizer, soil, and food analysis, 
the amount of phosphorus is expressed in terms of P 2 5 . 

108. Phosphoric Acid and Phosphates. — Ordinary 
phosphoric acid is produced by the action of H.,S0 4 upon 
bone ash. 

3 H 2 S0 4 + Ca 3 (P0 4 ) 2 = 2H 3 P0 4 + 3 CaS0 4 . 

Salts of ortho or ordinary phosphoric acid are the most 
common forms of the acid derivatives. Since this acid 
contains three replaceable H atoms, three salts are formed, 
as : Na 3 P0 4 , normal sodium phosphate ; Na 2 HP0 4 , di- 
sodium phosphate ; and NaH 2 P0 4 , monosodium phos- 
phate. The three calcium salts of phosphoric acid are : 

CaH 4 (P0 4 ) 2 , monocalcium phosphate. 

Ca 2 H 2 (P0 4 ) 2 , dicalcium phosphate. 

Ca 3 (POJ 2 , tricalcium phosphate. 

In addition to the ordinary phosphoric acid, there are 
other derivatives, as : 

H 3 P0 4 = H 2 + HP0 3 (metaphosphoric acid) . 

2H 3 P0 4 = H 2 + H 2 P 2 7 (pyrophosphoric acid). 

109. Phosphate Fertilizers. — In deposits of phosphate 
rock, the phosphoric acid is mainly in combination with 
calcium as Ca 3 (P0 4 ) 2 , and is of little value as plant 
food until it is treated with H 2 S0 4 and converted into 
monocalcium phosphate, which is soluble and available 
as plant food. Ca 3 (P0 4 ) 2 + 2H 2 S0 4 = CaH 4 (P0 4 ) 2 + 
2CaS0 4 . Large amounts of phosphates undergo this 
treatment in the manufacture of commercial fertilizers. 



PHOSPHORUS AND ITS COMPOUNDS 95 

Experiment 17. — In a beaker on a sand-bath, dissolve l j 2 gram 
of bone-ash in 10 cc. dil. HNO s + 20 cc. H 2 ; filter, and to the fil- 
trate, while still warm, add 5 cc. ammonium molybdate, and then 
stir. Observe the precipitate, which is a compound of phosphoric 
acid, ammonium, and molybdenum. 

Questions. ( 1 ) What was the solvent of the phosphoric acid ? 
{2) Why was the solution boiled and filtered ? (3) Describe the 
color and properties of the precipitate. 

Experiment 18. — Dissolve 1 / 2 gram of sodium phosphate in 
10 cc. distilled water, then add 10 cc. of a solution containing V 2 
gram CaCl 2 . Observe the result. Write the reaction. Repeat this 
experiment, using A1C1 3 or alum in place of CaCl 2 . 

1 10. Compounds of Phosphorus. — Phosphorus forms 
a large number of compounds, as phosphates, metaphos- 
phates, and pyrophosphates. It also combines with H, 
CI, and I. With H it forms PH 3 , phosphine, an analo- 
gous compound of NH 3 . Phosphorus also enters into 
combination with C, H, N, O, and S, forming complex 
organic compounds, as nucleated proteids and lecithin. 
It is an element which has a wide range of combinations. 

in. Importance of Phosphorus and Its Compounds. 

— The compounds of phosphorus, particularly the phos- 
phates, are important in plant development, being essen- 
tial forms of mineral food required for crop growth. 
Agriculturally considered, phosphorus is one of the most 
important of the elements. It is stored up in the seeds of 
grains, and in combination with the elements which form 
the organic compounds of plants, it takes an important 
part in animal nutrition. Compounds of phosphorus are 
used in the manufacture of matches, and as poison for in- 
sects. Phosphorus forms a large number of compounds 



96 AGRICULTURAL CHEMISTRY 

both with the metals and with the elements which enter 
into the organic compounds of plant and animal bodies. 

Problem 1. — How much P 2 5 in a ton of bones, 80 per cent. 
Ca 3 (P0 4 ) 2 ? 

Problem 2. — How much would the P 2 5 in a ton of Ca 2 H 2 (P0 4 ) 2 
be worth at 5 cents per pound for the P 2 3 ? 

Ca 2 H 2 (P0 4 ) 2 = P 3 5 + 2CaO + H 2 0. 



CHAPTER XIV 
Sulfur and Its Compounds 

112. Occurrence. — Sulfur is found free, and in combina- 
tion with other elements ; sulfids and sulfates are the 
compounds which occur the most abundantly. Sulfur is 
also found in small amounts, in combination with carbon, 
hydrogen, oxygen, and nitrogen, forming the organic 
compounds of plant and animal bodies. 

113. Preparation. — When taken from the mines, sulfur 
is mixed with impurities, as sand and clay, which are 
partially removed by 
heating the sulfur, out 
of contact with the air, 
much in the same way 
that charcoal is pro- 
duced. The Crude SUlfur FiS ' 43-Crystals of sulfur. 

is refined by vaporizing and condensing the volatile sulfur 
upon the surfaces of brick chambers, the product being 
known as flowers of sulfur. By drawing off the molten 
sulfur into wooden molds, roll sulfur, or brimstone, is 
formed. 

114. Properties. — Like carbon and a few other ele- 
ments, sulfur has a number of allotropic forms. It may 
assume either an amorphous or several crystalline forms. 
It melts at a low temperature, and when molten sulfur is 
poured into water, a rubber-like, amorphous mass is 
obtained. Sulfur combines with oxygen ; and with the 
metals it forms sulfids. 




98 AGRICULTURAL CHEMISTRY 

115. Uses. — Sulfur is used in the preparation of sulfuric 
acid, in the production of vulcanized rubber, in the 
manufacture of matches and gunpowder, and for bleach- 
ing and disinfecting purposes. A small amount in the 
form of sulfates is necessary as plant food. 

Experiment ig. — Properties of sulfur. Place 15 grams of 
sulfur in a test-tube and heat slowly until it is a thin, amber-colored 
liquid. As the heat increases, notice that it becomes darker until 
black, and so thick and viscid that it cannot be poured from the 
test-tube. Continue to apply heat until slightly lighter in color 
and again a liquid. Then pour the sulfur into an evaporating dish 
containing water, and, when cold, examine it and describe its proper- 
ties. Examine the sulfur product or crystals left in the test-tube, 
and compare with the original sulfur, using a lens for the purpose. 

Questions. (1) Are the crystals of sulfur formed by fusion like 
those of the original powdered form ? (2) How is it possible for 
sulfur to assume different physical forms ? (3) Is sulfur soluble in 
water? (4) What is a sulfate ? Give the formula for one. (5) What 
is a sulfite ? Give the formula for one. (6) What is a sulfid ? 

116. Sulfur Dioxid. — When sulfur is burned either in 
air or oxygen, S0 2 , a colorless, suffocating, non-combusti- 
ble gas is produced. S0 2 combines with water, forming 
H 2 S0 3 , sulfurous acid. Sulfur dioxid is used in bleach- 
ing and for disinfecting purposes, as it is alike destruc- 
tive to organic coloring-matter and to germ life. 

Experiment 20. — Sulfur dioxid. Fill the deflagration spoon - 
half full of sulfur ; ignite, and then lower into a small cylinder con- 
taining a piece of wet colored cloth and a piece of wet blue litmus 
paper. As soon as the sulfur ceases to burn, remove the spoon and 
cover the cylinder with a glass plate. 

Questions. (1) What reaction does the S0 2 give with the litmus 
paper? (2) What effect does it have upon the cloth? (3) What 
does the S0 2 form with H a O ? (4) Is S0 2 a heavy or light gas ? (5) 



SULFUR AND ITS COMPOUNDS 99 

Is it a chemically active substance ? (6) Why does it act as a 
bleaching agent ? (7) Why is it valuable as a disinfectant ? 

117. Sulfuric Acid — Sulfuric acid can not be produced 
from sulfates as HC1 and HN0 3 were produced from their 
salts, because there is no acid or other material that can 
be used economically for the purpose. H 2 S0 4 is made 
from its elements by the use of an oxidizing agent. The 
different steps in its production are : 

( 1 ) Burning of sulfur, or roasting of some ore, as 
pyrites, which contains sulfur. The S forms with O, S0 2 . 

(2) Union of S0 2 and H 2 0, forming sulfurous acid, 
H 2 S0 3 . 

(3) Oxidation of H 2 SO s to form H 2 S0 4 . This is accom- 
plished by the use of N0 2 reduced to NO, which in turn 
is capable of uniting with the oxygen of the air, re- 
forming N0 2 . NO is used as a carrier of O ; hence the 
oxygen of the air is used indirectly for the oxidation 
of H 2 S0 3 . The different reactions take place .simulta- 
neously in lead-lined chambers : 

S0 2 + H 2 + N0 2 = H 2 S0 4 + NO. 
NO -f O = N0 2 . 
Other and more complicated reactions also take place. 

The crude acid is then concentrated and purified. Sul- 
furic acid is extensively used in industrial operations. 
There is scarcely a chemical product in the preparation of 
which H 2 S0 4 has not been used either directly or in- 
directly. H 2 S0 4 takes an important part in the manufac- 
ture of soda, which, in turn, is used for making glass ; in 
the preparation of commercial fertilizers, and of many 
food products. The amount of sulfuric acid which a 

L.ofC. 



IOO AGRICULTURAL CHEMISTRY 

country consumes is a fair index of the extent of its 
manufacturing industries. 

118. Properties of H 2 S0 4 — When pure it is a colorless, 
heavy, oily liquid. It has a strong affinity for water, 
with which it combines with evolution of heat. It will 
decompose organic materials containing C, H, and O, 
liberating the H 2 as water, with which it combines, 
while the carbon, which is partially oxidized, separates 
and blackens the acid. When sugar is acted upon by 
concentrated sulfuric acid, this change takes place. 
H 2 S0 4 is used in the laboratory for drying gases, for 
drying the air in desiccators, and for oxidizing purposes, 
as in the determination of organic nitrogen in food mate- 
rials. It is one of the most useful and extensively used 
of any of the reagents in the laboratory. 

Experiment 21.— Make the following tests with some of the 
sulfuric acid from the reagent bottles : ( 1 ) Put 2 or 3 cc. H 2 S0 4 
into a test-tube ; thrUst a splinter of wood into it and leave it there 
for a few minutes. Then remove the splinter from the test-tube. 
Wash off the acid and examine the splinter. (2) Place in an 
evaporating dish 5 cc. water and 15 cc. H 2 S0 4 . Stir it with a small 
test-tube containing 1 or 2 cc. NH 4 OH. Observe that the heat 
generated by the action of the H 2 S0 4 and water, volatilizes some of 
the NH 3 . (3) Put 10 cc. of water and 1 cc. of H 2 S0 4 into a test- 
tube. Then add 2 or 3 cc. of barium chlorid, BaCl 2 . Observe the 
result. 

Questions. (1) Why is not H 2 S0 4 made from sulfates? (2) 
Why is heat produced when water and H 2 S0 4 are mixed ? (3) 
What use was made of this heat in test No. 2? (4) What caused 
the precipitate when BaCl 2 was added? (5) Write the reaction. 
(6) What is the name of the product formed ? (7) What are some 
of the uses of H 2 S0 4 ? (8) How many kinds of salts does H 2 S0 4 



SULFUR AND ITS COMPOUNDS IOI 

form ? (9) Why is nitric oxid used in the manufacture of H 2 S0 4 ? 
(10) What are the physical properties of H 2 S0 4 ? (n) Of what 
agricultural value is H 2 S0 4 ? (12) Does H 2 S0 4 dissolve lead ? (13) 
Why does commercial H 2 S0 4 often appear dark-colored or deposit 
a fine white sediment ? 

119. Sulfates. — Sulfuric acid is a dibasic acid, and 
hence may form two series of salts, as NaHS0 4 , primary 
sodium sulfate (acid sodium sulfate) , and Na 2 S0 4 , second- 
ary sodium sulfate (normal sodium sulfate). The sul- 
fates of the metals form a large class of compounds which 
vary in chemical and physical properties according to the 
metal that is present. The sulfates as a class are fairly 
stable compounds ; some, as sodium and potassium sul- 
fates, are soluble ; others, as calcium sulfate, are sparingly 
so while barium sulfate is one of the most insoluble sub- 
stances in nature. Many of the sulfates contain water of 
crystallization. Some, as calcium and potassium sulfates, 
are valuable as fertilizers, while others, as copper sulfate, 
are used as fungicides. 

120. Sulfids. — Sulfids are compounds of the metals 
with sulfur, as K 2 S, FeS, and CuS. When a sulfid, as 
FeS, is treated with a dilute acid, H 2 S, hydrogen sulfid, 
is liberated. FeS + 2HCI == FeCl 2 + H 2 S. 

The differences in solubility and other properties of the 
sulfids are taken advantage of in the separation and 
identification of the metals. H 2 S is formed when albu- 
minous matter, as the white of an egg, decays. It is also 
present as one of the gases given off from sewers. It is a 
poisonous, suffocating gas. 

Experiment 22. — Hydrogen sulfid, (This experiment should 



102 



AGRICULTURAL CHEMISTRY 



be performed under the hood). Arrange the apparatus as 
shown in Fig. 44. The delivery tube and cork should fit tightly, 
and the delivery tube should pass into a test-tube containing 10 cc. 
of Pb(N0 3 ) 2 solution. Test-tubes containing 10 cc. 
respectively of NaCl, and CuS0 4 solutions should 
be conveniently at hand. Place 5 grams of pul- 
verized FeS in the generating test-tube, add 10 cc. 
dilute HC1, and immediately connect with the de- 
livery tube. After the gas has passed through the 
lead nitrate solution, for a couple of minutes, pass 
it through the sodium chlorid and copper sulfate 
solutions ; then allow a little of the gas to escape 
into a cylinder containing water. Do not allow 
the free gas to escape in the room. With NaCl no 
insoluble sulfid is formed. 

Questions. ( 1 ) What is the odor of the gas ? ( 2 ) 
Write the equation for its production. (3) What 
was formed when the gas was passed into Pb(N0 3 ) 2 ? 
Write the reaction. (4) What was formed when 
the gas was passed through Cu(N0 3 ) 2 ? Write the 
reaction. (5) Is H 2 S soluble in water ? (6) When albumin decays, 
from what is the H 2 S produced? (7) Why was no precipitate 
formed when the gas was passed through NaCl ? 

Problem 1. — How much H 2 S0 4 can be made from one ton of sul- 
fur? 

Problem 2. — What per cent, of H 2 S0 4 is S0 3 ? 
Problem 3.— How much H 2 S0 4 is required to neutralize 500 
pounds NaOH ? 




Fig. 44.— Hydro- 
gen sulfid gen- 
erator. 



CHAPTER XV 
Silicon and Its Compounds 

121. Occurrence. — Silicon is found in nature in com- 
bination with oxygen as silica, Si0 2 ; and with oxygen 
and the metals as silicates. It is never found free but al- 
ways in combination with other elements. Next to 
oxygen it is the most abundant element found in nature. 
In the form of silicates it is the basis of the composition 
of nearly all rocks, and in the soil Si0 2 is found to the 
extent of from 60 to 90 per cent. It is present in the 
ash of plants and, to a slight extent, in animal bodies. 

122. Preparation and Properties. — Silicon is separated 
from its compounds with difficulty. By treatment in an 
electric furnace, quartz or Si0 2 is reduced. 
Like carbon, silicon has crystalline and 
amorphous forms. Pure quartz, Si0 2 , 
and other forms of silicon, are insoluble 
in nitric, hydrochloric, and sulfuric acids. 
When acted upon by hydrofluoric acid, 
silicon tetrafluorid, a gas is formed. 

Fig- 4S- 
Si0 2 + 4HF = SiF, + 2H 2 0. HF is Quartz crystal. 

used extensively for the decomposition of silicates. 

123. Silicic Acid.— When Si0 2 is fused with the hy- 
droxids or carbonates of potassium or sodium, potassium 
or sodium silicate is obtained : 

Si0 2 + K,C0 3 = K 2 Si0 3 + C0 2 . 
Si0 2 + 4KOH = K 4 Si0 4 + 2H 2 0. 
The silicates of potassium and sodium are soluble in 




104 



AGRICULTURAL CHEMISTRY 



water, and are commonly called water-glass. Some of 
the silicates are soluble in acids, but most of them are 
insoluble complex compounds which are difficult to de- 
compose. 

When K 4 Si0 4 is treated with HO, a gelatinous mass 
containing silicic acid is obtained : K 4 Si0 4 + 4HCI = 
H 4 Si0 4 + 4KCI. 

H 4 Si0 4 is normal silicic acid. Upon exposure to the 
air it loses a molecule of water and forms ordinary silicic 
acid, H 2 Si0 3 , which is decomposed by heat and in the 
presence of acids forms H 2 and Si0 2 . 

In addition to the two silicic acids, H 2 Si0 3 and H 4 Si0 4 , 
there are other forms known as polysilicic acids as : 
H 2 Si 3 7 , H 4 Si 3 8 , and H 2 Si 2 5 , obtained by removing 
water from the normal and ordinary silicic acid. 
2H 2 Si0 3 = H 2 Si 2 5 + H 2 0. 
3 H 4 Si0 4 = H 4 Si 3 8 + 4H 2 0. 
124. Dialysis. — In the preparation of silicic acid, the 
process known as dialysis is employed for dissolving and 
removing the impurities. Some sub- 
stances, as NaCl and HC1, dissolve 
and readily pass through animal mem- 
brane ; such substances are called 
crystalloids, while bodies like silicic 
acid, which do not penetrate animal 
membrane, or do so very slowly, are 
called colloids. The removal of the 
HC1 from the solution containing the 
gelatinous silicic acid is accomplished by means of the 
dialyzer, Fig. 46. This property of materials, readily or 





Fig. 46. — Dialyzer. 



SILICON AND ITS COMPOUNDS IO5 

slowly to diffuse through animal membrane, is a physical 
characteristic, and is occasionally made use of for wash- 
ing and separating compounds. 

125, Silicates. — Since silicon forms such a variety of 
acids, the number of silicates found in nature is very 
large. The hydrogen atoms of silicic acid can be re- 
placed with different metals, forming double salts, as 
AlKSi 3 Og, which is feldspar, or the double salt of trisilicic 
acid, H 4 Si 3 O g . This renders the composition of the sili- 
cates exceedingly complex. Many of the silicates con- 
tain also water of hydration as part of the molecule ; as 
aluminum silicate or pure clay, AL c (Si0 4 ) 3 .H 2 0. Since 
rocks are composed mainly of silicates, and soils are 
formed from the decay of rocks, it follows that soils are 
practically a mechanical mixture of silicates with small 
amounts of other compounds. Hence, the importance of 
the subject of silicic acid and the silicates. Unfortunately 
the structure and composition of the silicates have not 
been determined as completely as of other salts and 
acids. Pure clay is aluminum silicate, formed from the 
disintegration of feldspar rock, a double silicate of potas- 
sium and aluminum. Mica, hornblende, and zeolites 
are all complex forms of silicates. 

126. Importance of Compounds of Silicon. — The com- 
pounds of silicon, as silicon dioxid, Si0 2 , and of the sili- 
cates, are used in the manufacture of glass, porcelain and 
brick. The element itself takes no direct part in animal 
or plant life, but indirectly is important, for it is in 
combination with many elements which serve as plant 
food. Some of the simpler and more soluble silicates are 



106 AGRICULTURAL CHEMISTRY 

capable of being acted upon by decaying animal and 
vegetable matter and undergoing chemical changes which 
prepare them for plant food. Since silicon forms the 
principal acid element which enters into the composition 
of rocks, soils, building stones, glass, brick, and porcelain, 
and is associated with the elements in the soil which serve 
as plant food, it follows that it is an important element in 
industrial operations and in agriculture. 

Experiment 23. — To about 5 cc. of sodium silicate in a test-tube 
add a few drops of HC1 and observe the result. Then add NaOH 
and observe the result. Add more HC1, and evaporate the ma- 
terial to dryness in the evaporating dish. When cool, test the 
solubility of the residue in water. 

Questions. (1) What was formed when HC1 was added to 
sodium silicate ? Write the reaction. (2) What was the appearance 
of the above product ? (3) What effect did the NaOH have, and 
what was formed ? (4) What was formed when the material was 
evaporated to dryness? (5) What can you say as to the solubility 
of the product ? 

Problem 7.— What per cent, of Si0 2 in clay, Al 4 (Si0 4 ) 3 .H 3 0? 

Problem 2. — How much silicic acid is formed when 10 grams of 
HC1 act upon K 4 Si0 4 ? 



CHAPTER XVI 
Oxids of Carbon, Carbonates, and Carbon Com- 
pounds 

127. Carbon Dioxid. — Carbon dioxid is obtained from 
the combustion of carbon and also from the treatment of 
a carbonate with an acid. A carbonate is a salt of car- 
bonic acid, M 2 C0 3 , in which M represents any mono- 
valent metal, as K or Na. Calcium carbonate, CaC0 3 , is 
the most abundant carbonate found in nature. When a 
carbonate is treated with an acid C0 2 is liberated, and a 
salt is formed, as 

CaC0 3 + 2HCI = CaCl 2 + C0 2 + H 2 0. 

Experiment 24. — Preparation of carbon dioxid. Arrange the 
apparatus as for the preparation of hydrogen. Put 10 grams of 
marble, CaC0 3 , into the Woulff bottle, and sufficient water to 
cover the end of the thistle tube. Fill 2 or 3 cylinders with water 
for collecting the gas, which is only slightly soluble in water, then 
add slowly, through the thistle tube, about 20 cc. concentrated 
HC1. Allow a little of the first gas generated to escape into the 
room and then collect 2 or 3 cylinders of C0 2 . Remove the cylinders 
from the pneumatic trough and place them on the desk, right side 
up. Now remove the delivery tube from the pneumatic trough 
and allow the gas to pass into a test-tube containing about 10 cc. of 
clear lime water, Ca(OH) 2 . If necessary, add through the thistle 
tube a little more acid to the generator. Observe the white precipi- 
tate formed in the test-tube. Let the gas pass through the lime 
water for several minutes, until the solution becomes clear. Now 
boil the solution and observe the reappearance of the white precipi- 
tate. Test some of the escaping gas with a burning splinter. 
Pour a receiver of the gas over a candle or a low gas flame, and 
observe the result. Thrust a burning splinter into a cylinder of 



108 AGRICULTURAL CHEMISTRY 

C0 2 . Observe the result. Add 5 cc. water to the cylinder in which 
the splinter was placed, and then a little lime water ; shake, and 
observe the result. 

Questions. (1) Write the reaction for the preparation of C0 2 . 
(2) What is a carbonate? (3) Is CaC0 3 soluble in pure water? 
(4) Is it soluble in water containing C0 2 ? (5) What caused the 
precipitate to form when the C0 2 gas was passed through the lime 
water? (6) What is this precipitate? Write the reaction. (7) 
What caused this precipitate to disappear when more gas was 
passed through the solution? (8) What caused it to reappear 
when the solution was boiled? (9) What caused the candle to be 
extinguished when a receiver of C0 2 was poured over the flame ? 
(10) is a supporter of combustion ; C0 2 contains O ; why does 
C0 2 not support combustion? (11) Is C0 2 a heavy or a light gas, 
and what tests indicate that it is heavy or light? (12) What other 
carbonate could be used for making C0 2 ? (13) What other acid 
could be used for making C0 2 ? 

128. Carbon Monoxid.— Carbon monoxid is formed 
when carbon is only partially oxidized because of an in- 
sufficient supply of air. In a coal stove, for example, 
there is not a perfect supply of air in the interior of the 
burning mass ; carbon monoxid is formed there and passes 
to the surface where it burns as a blue flame. If the 
draft is imperfect, a large amount of carbon monoxid is 
formed. When a coal stove gives off gas, the carbon 
monoxid is not oxidized, but is thrown off into the room. 
Carbon monoxid is a light, colorless, combustible, poison- 
ous gas, and can be produced by subjecting highly heated 
carbon to the action of steam. The reaction is 
C -f H 2 = CO + 2H. Both CO and H are combustible, 
and when they are enriched by some of the hydrocarbons, 
so as to introduce materials for producing light, when 
burned, they may be used for illuminating purposes, and 



OXIDS OF CARBON, CARBONATES, ETC IO9 

the product is called water-gas. Carbon monoxid is pro- 
duced in furnaces from the coke, which is mixed with ore, 
and in the smelting and refining of ores, carbon monoxid 
is an important reducing agent ; in fact, it is the main 
reducing agent of the blast-furnace. 

129. Marsh Gas (Methane, CHJ. — When vegetable 
matter decays under water, where the supply of air is 
incomplete, methane, CH 4 , is one of the products formed. 
It is given off in bubbles from the surface of stagnant 
pools. It often collects in coal mines, and is there called 
fire-damp. CH 4 can be prepared in the laboratory in a 
number of ways, and is a colorless, combustible gas, 
which with air forms an explosive mixture. 

130. Hydrocarbons. — A compound, as methane, com- 
posed of hydrogen and carbon, is called a hydrocarbon. 
There are a large number of such compounds, forming 
series in which the members differ from one another 
in composition by a definite number of C and H atoms, 
as methane, CH 4 , and ethane, C 2 H 6 . The next mem- 
ber is propane, C 3 H 8 ; CH 2 being the common difference 
between the members of this series. By oxidation, re- 
duction, and substitution, in which a part of the H is re- 
placed with equivalent radicals, a large number of de- 
rivatives, as alcohols, aldehydes, ethers and organic 
acids, are formed. 

131. Petroleum. — Petroleum is an oily liquid obtained 
in some parts of the world by boring wells into the rock 
strata in which it is found as a natural product. It is 
a mechanical mixture of various liquid and solid hydro- 



no 



AGRICULTURAL CHEMISTRY 



carbons, often accompanied with gaseous hydrocarbons. 

The hydrocarbons distilled off at a low temperature, rang- 
ing from 8° to 68° C, form 
the gasoline and benzine prod- 
ucts, while those which distil 
between 175 and 215 C. form 
the various grades of kerosene. 
In the preparation of gasoline, 
benzine, and kerosene, the sep- 
aration of the various grades 
of hydrocarbons is not com- 
plete ; kerosene, for example, 
may contain traces of either 
gasoline or paraffin products. 
Kerosene should have a flash- 
ing-point not below 44 C. 
( 1 1 1 ° F. ) , in order to render 
''Wit safe for illuminating pur- 
poses. The flashing-point of 
kerosene may be approxi- 
mately determined in the fol- 
lowing way : 

, Experiment 25. — Testing kero- 
sene. Pour into a small porcelain 
crucible some kerosene ; place the 
crucible upon a water-bath, and sus- 
pend a thermometer in the kerosene. 
Do not allow the water in the bath 
to come in contact with the cruci- 
Fig. 47.-Testing kerosen e. Wg Qr the thermometer to touch the 

bottom. Cautiously heat the water until the thermometer registers 
40 C, then remove the lamp and draw a lighted match across the 




OXIDS OF CARBON, CARBONATES, ETC. Ill 

surface of the kerosene. If it flashes, note its temperature ; do not 
let it burn ; should this occur, remove the thermometer and cover 
the crucible. If the kerosene does not flash, repeat the test and if 
necessary apply more heat until the flashing-point is reached. Cal- 
culate the corresponding temperature on the Fahrenheit scale. 

132. Use of Gasoline. — Gasoline is perfectly safe for 
use as a fuel, provided a few simple precautions are ob- 
served : ( 1 ) Never use a gasoline stove when there is 
but little gasoline in the tank, because the last gas gen- 
erated is mixed with air, and is liable to form an explo- 
sive mixture. (2) All joints and connections about the 
stove should be tight to prevent escape of gasoline into 
the air. Lack of care in this respect is the most frequent 
cause of fires. (3) The gasoline can should be well 
corkedjand stored in a cool place. (4) The stove should be 
kept clean, and no deposit of carbon should be allowed to 
collect upon the burners. 

133. Illuminating Gas. — Illuminating gas is made from 
soft coal and petroleum by destructive distillation. The 
gases formed are washed and separated from ammonia 
and coal-tar, and consist of various hydrocarbons which 
are used for illuminating purposes. The coal, after being 
deprived of its gaseous products, is converted into coke, 
which bears the same relation to coal which charcoal bears 
to wood. The ammonia and coal-tar are recovered as by- 
products. Various coloring-matters are made from coal- 
tar. 

If air is forced through gasoline in a confined chamber, 
or if gasoline is vaporized, it will burn like ordinary coal 
gas. Gasoline can be vaporized on a small scale, and 



112 



AGRICULTURAL CHEMISTRY 



machines suitable for the purpose are made for illuminat- 
ing dwellings. Five gallons of gasoline will produce, about 
iooo feet of gas or vapor. The illuminating power of 
gas, and of flames in general, is expressed in terms of 
candle-power. A sixteen candle-power light is one that 
gives sixteen times as much light as a standard candle, 




Fig. 48. — Illuminating gas plant for producing gas from gasoline. A, weight 
to air-pump B. D, carburetter or generating tank into which air is forced. 

composed of spermaceti, and burned at the rate of 120 
grains per hour, the comparison being made by means of 
a photometer. In some localities, hydrocarbons, due to 
decomposition of organic matter, are given off from the 
earth as natural gas in amounts sufficient to be used for 
illuminating and fuel purposes. 

134- Mineral Oils.— The heavier products obtained in 



OXIDS OF CARBON, CARBONATES, ETC. 113 

the distillation of petroleum, after the removal of the 
gasoline, benzine, and kerosene, are used for lubricating 
purposes, and are called mineral oils. They have a boil- 
ing-point from 250 to 350 C. 

135. Oil of Turpentine (C 10 H 16 ). — Oil of turpentine is 
obtained by distilling the resinous material which exudes 
from incisions in certain species of pines. Resin is ob- 
tained in the retorts. Oil of turpentine is inflammable, 
and dissolves readily in ether, alcohol, and naphtha. It 
is a valuable solvent, extensively used in the preparation 
of varnishes and paints, and as a solvent for caoutchouc. 
Turpentine belongs to the class of compounds known as 
essential oils. 

136. Creosote. — When wood tar is distilled, various 
products are obtained which, after treatment with chemi- 
cals for purification, are called wood-tar creosote. This 
is a yellowish liquid with a smoky odor. It is a power- 
ful antiseptic, and is the preservative employed in the 
preparation of " smoked meats." as hams and fish. It 
has no marked action on albuminous matter and in small 
amounts is not poisonous. Because of its antiseptic powers, 
wood creosote is used extensively for the preservation of 
wood, as it prevents decay. When some kinds of wood, 
as beech wood, are burned, the wood-tar condenses in 
the chimney. 

137. Benzine or Benzol (C,.H 6 ). — When coal tar, ob- 
tained in the manufacture of illuminating gas, is sub- 
jected to fractional distillation, commercial products are 
obtained known as coal tar, naphtha, middle oil, heavy 



114 AGRICULTURAL CHEMISTRY 

oil, anthracene oil, and pitch or artificial asphaltum. The 
naphtha or light oil consists of a mixture of hydrocar- 
bons, benzine being among the number. Benzine is ex- 
tensively used as a solvent for fatty bodies. It is a very 
inflammable liquid. 

i38. Aliphatic and Aromatic Series of Compounds. — 
In organic chemistry benzine occupies an important posi- 
tion, as the direct treatment of benzine and its deriva- 
tives, produces the aromatic series of compounds, which 
form one of the two main divisions of the subject. The 
other is obtained from methane and its derivatives, 
and constitutes the aliphatic series. The alcohols, ethers, 
glycerides, fatty acids, organic acids, carbohydrates, and 
amids, are members of the aliphatic series, while essen- 
tial oils, coloring-matters, and mixed nitrogenous com- 
pounds, are members of the aromatic series. In or- 
ganic chemistry, a study is made of the formation, 
relationship, structure, and properties of all these com- 
pounds. Hence the importance of this branch of chem- 
istry . 

139. Carbon Disulfid. — With sulfur, carbon forms car- 
bon disulfid, CS 2 , a clear liquid with a characteristic odor. 
It readily burns and is easily vaporized. It is a solvent 
for fats, resins, sulfur, and iodin, and is used for the de- 
struction of insects, particularly those infesting grains, 
and for killing small burrowing animals, as gophers. 

140. Cyanids. — In the presence of metals carbon unites 
indirectly with nitrogen, forming cyanids as KCN. When 
mercuric cyanid is heated, cyanogen gas and metallic 
mercury are formed : Hg(CN) 2 = Hg + 2CN. Cyano- 



OXIDS OF CARBON, CARBONATES, ETC. 115 

gen and the cyanids are very poisonous. With H, cyano- 
gen forms hydrocyanic acid, which is used for the destruc- 
tion of scale insects and in the preparation of pigments. 

141. Carbids. — With some of the metals, notably cal- 
cium, carbon forms carbids, as CaC 2 , which is produced 
by the fusion of coke and limestone in electric furnaces. 
In the presence of water CaC 2 is decomposed, forming 
acetylene gas, C 2 H 2 , and calcium hydroxid. 

CaC 2 + 2H 2 = C 2 H 2 -f- Ca(OH) 2 . 
Acetylene generators are prepared for illuminating 
dwellings. Acetylene, like all gaseous hydrocarbons, as 
methane and benzine, forms explosive mixtures with oxy- 
gen. All illuminating gases should be dealt with as 
highly combustible and explosive materials. 

142. Fuels. — There are three forms of fuel : (1) gas, 
(2) liquid, and (3) solid. Natural gas, coal gas, and gas 
generated from gasoline and naphtha, are the principal 
forms of gas fuel ; kerosene, gasoline, and crude petro- 
leum are liquid fuels, while coal, coke, lignite, peat, and 
wood are the chief forms of solid fuel. The composition 
of coal, coke, lignite, and peat, is discussed in Chapter V. 
Wood is composed largely of cellulose, and contains, when 
dry, about 50 per cent, carbon, 6 per cent, hydrogen, and 
43 to 44 per cent, oxygen. Air- dried wood contains from 
10 to 15 per cent, moisture. Different kinds of wood 
vary in density between quite wide limits; for example, 
a cord of dry pine weighs about 3000 pounds, while a 
cord of dry maple or other hard wood weighs from 4500 
to 5000 pounds, or more. Hence the same volume (as a 
cord) of soft wood yields less total heat than a cord of 



Il6 AGRICULTURAL CHEMISTRY 

hard wood, but a pound of the different kinds of wood 
gives nearly the same amount of heat. The amount of 
heat which a material produces when burned is measured 
in the calorimeter, and is given in terms of calories or 
heat units. The presence of water in fuels lowers their 
caloric value, because it requires a definite amount of 
heat to evaporate and expel as steam the moisture before 
combustion can take place. 

143. Caloric Value of Fuels (Comparison made on 
basis of equivalent weights) . 

Calories. Calories. 

Perfectly With Per cent, of 

dry. water. water. 

Hard coal 9160 8690 2.63 

Soft coal 7664 7128 5.02 

Pine (red) 5997 5155 13.83 

Cedar 5974 5031 14.09 

Maple 5978 5117 12.49 

Birch 5978 4758 21.70 

144. Foods. — The materials used as human and animal 
foods are mechanical mixtures of various organic com- 
pounds, as starch, sugar, fat, albumin, etc., together 
with various mineral salts. The composition of the or- 
ganic compounds of foods forms a part of the study of 
organic chemistry, while their economic value and the uses 
made of them by the body, are studied in physiological 
chemistry. Knowledge in regard to the composition and 
uses of foods, particularly of human foods, is somewhat 
limited, although along this line, many facts and laws of 
economic and sanitary importance have been discovered. 
The subject of foods is treated more fully in the chap- 
ters relating to the chemistry of foods. 



OXIDS OF CARBON, CARBONATES, ETC. 



II' 



PLANT FOOO 



Vegetable foods and fuels are alike in chemcal com- 
position, and serve somewhat the same functions, 
but in different ways. Food is used as fuel by the body, 
and also for the renewal of old and the production of new 
tissues. The heat produced from food is transformed 
into muscular and other forms of energy ; the heat from 
the combustion of fuel is converted into chemical energy, 
which is utilized for mechanical purposes. 

145. Production of Organic Compounds in Plants. — 
The carbon dioxid of the air is the source of the carbon 
used by plants 
for the produc- 
tion of the 
various organic 
compounds 
found in vegeta- 
ble substances, 
and since about 
50 per cent, of 
the ash-free tis- 
sue of plants is 
carbon, it fol- 
lows that the 
carbon dioxid 
of the air is an 
important fac- 
tor in plant 




Fig. 49. 



-Production of organic compounds in plants, 
showing sources of plant food. 



growth. Hydrogen and oxygen are obtained from 
the water of the soil which is received from the 
air. The production of the various organic com- 



Il8 AGRICULTURAL CHEMISTRY 

pounds of plants takes place in the cells of the 
leaves, and is the result of chemical changes induced by 
life processes. In order to promote cell activity, sun- 
light and a suitable temperature are necessary. The 
sun's rays take an important part in promoting chemical 
changes in the leaves of plants. In addition to carbon 
dioxid, water, heat, and sunlight, various mineral ele- 
ments in the form of compounds of potassium, calcium, 
phosphorus, nitrogen, iron, magnesia, sulfur, and pos- 
sibly of a few others are required as plant food. Without 
these essential elements and requisite conditions, the 
growth of crops cannot take place. It often happens that 
soils are unproductive because of the absence, in available 
form, of some of the elements essential for plant life. 
The production in the leaves of plants of the various or- 
ganic compounds, as cellulose, starch, sugar, fat, albu- 
min, etc., and a few of the complex chemical changes 
which take place, have been studied. 

146. Decay of Organic Compounds. — All organic com- 
pounds, particularly those found in the tissues of plants 
and used as food, are subject to chemical change com- 
monly called decay. Such change is nearly always pro- 
duced as the result either of the action of organized fer- 
ments, or of the chemical products known as chemical 
or soluble ferments. Fermentation changes and decay 
take place whenever cell activity becomes feeble or 
ceases ; then the material becomes food for micro-organ- 
isms. Many chemical changes take place as the result of 
fermentation ; some of these are necessary in plant and 
animal nutrition. If the chemical changes, coordinate 



OXIDS OF CARBON, CARBONATES, ETC. 



119 



EC 



f 3 ^ 



I 




with fermentation, are uninterrupted, the organic mate- 
rials are decomposed until carbon dioxid, water, ammonia 
gas, and hydrogen sulfid are ob- 
tained as the final products. 
When such changes take place, 
the mineral matter combined and 
associated with the organic mat- 
ter is left as non-volatile products. 
In economic agriculture, it is the 
aim to conserve and return to the 
soil these essential elements, as 
nitrogen, potassium, phosphorus, 
and calcium, which are fre- 
quently unavailable or present in 
scant amounts in soils, so that 
the fertility will not be impaired. 
The elements present in plant and animal bodies pass 
through a cycle of chemical changes ; they are never lost 
to nature, but appear in different chemical compounds, as 
exemplified by the law of indestructibility of matter. 
A. Elements of plant growth in soil and air. 

B. Elements from soil and air elab- 
orated into plant tissue. 

C. Elements in plant tissue elab- 
orated into animal tissue. 

The elements in either plant or ani- 
mal bodies may pass back to A, and 
then pass again through the same 
cycle of chemical changes. 



Fig. 50. — Decay of wood. 




CHAPTER XVII 
Writing Equations 

147. Importance. — A chemical equation expresses con- 
cisely the changes which take place when two or more 
compounds are brought together so as to react, or when 
a material is acted upon by any agent which causes a 
chemical change. When chemical equations are under- 
stood by the student, they are of great assistance, as they 
necessitate a knowledge of the laws of valence, of the 
power of replacement, and of the properties of the ele- 
ments and their compounds. 

148. Common Errors in Writing Equations. — Some 
of the more common errors in writing equations are : 

(1). Failure to use correct formulas. 

(2). Failure to use the correct number of parts of com- 
pounds, radicals, or elements. 

(3). Failure properly to balance the equation. 

(4) . Failure to form reasonable compounds or products. 

If the correct formula, or the right number of mole- 
cules is not used, the equation is incorrect, it cannot be 
balanced, and the principle represented by the sign of 
equality is violated. There should be as many atoms of an 
element on one side of an equation as on the other. In 
order properly to balance an equation, as many mole- 
cules of the compounds on the left of the equation should 
be taken as are needed to satisfy the valences of the re- 
acting elements and radicals. In the equation 
AgN0 3 + HC1 = AgCl + HNO3, 



WRITING EQUATIONS 



121 



B 




only one molecule each of AgN0 3 and HC1 is necessary, 
because all of these elements and radicals are monova- 
lent. A simple exchange takes place in which the H of 
the acid is replaced by the metal Ag. If the elements H 
and Ag were to exchange places, they would occupy, 
after the exchange, the positions shown on the right-hand 
side of the equation. This exchange is represented 
graphically in Fig. 52 ; A represents the order before, 
and B after the reac- 
tion. Blocks of 
wood marked to rep- 
resent the elements 
and radicals can be 
used, the block marked 
H being replaced by 
the equivalent block 
marked Ag. When difficulty is experienced in writing 
chemical equations, this method of illustration will be 
found helpful. 
In an equation as 

2NaCl + H 2 S0 4 = Na.SO, + 2HCI, 
where both monovalent and bivalent elements and rad- 
icals are present, it is necessary to take two molecules 
of NaCl because there are two H atoms to be replaced. 
H and Na have the same valence, viz., 1, and S0 4 has a 
valence of 2. In order to obtain two atoms of Na, it is 
necessary to take 2NaCl ; then two atoms of Na replace 
two of H. The products are Na 2 S0 4 and 2HCI. S0 4 is 
a radical with a valence of 2 and requires 2Na atoms in 
order to form a compound. A similar reaction is repre- 



Fig. 52. — Graphic illustration of a chemical 
reaction. 



122 



AGRICULTURAL CHEMISTRY 




sented graphically by the use of blocks in Fig. 53. A 
represents the arrangement before, and B the arrange- 
ment after the reac- 
tion. Observe that in 
this equation there is 
the same number of 
atoms of each element 
on each side of the 
equation. After writ- 
ing an equation the 
student should always 
observe whether or 
not it is properly bal- 
anced, and that rea- 
sonable products are 
formed. The valences of the elements and radicals are 
given in Sections 15 and 77. 

There are always as many parts by weight of the ele- 
ments on one side of an equation as on the other. That 
is, the sum of the weights of the atoms and molecules on 
one side is equal to the sum of those on the other, as : 



B 



K' 




K' 



-}• 



H' 


no; 


H' 


no; 



Fig- 53- — Graphic illustration of a chemical 
reaction. 



2NaCl 


+ 


H a S0 4 = 


= 2HCI 




+ 


Na,S0 4 . 


2Na = 46 




2H= 2 


2H = 


2 




2Na = 46 


2CI =71 




S =32 
4O =64 


2CI = 


7i 




S = 32 
4O = 64 


117 




98 




73 




142 


117 + 98 = 215. 




7: 


,+ 


142 = 215. 



In the case of trivalent and bivalent elements and radi- 
cals, as in the reaction between H,P0 4 and Ca(OH)„ it 



WRITING EQUATIONS 1 23 

is necessary to take 2H 3 P0 4 and 3Ca(OH) 2 , in order to 
make the equation balance. The Ca and H atoms ex- 
change places ; there are three H atoms to be replaced. 
Ca has a valence of 2 ; 1 Ca cannot replace 3H, but 
6H(2H 3 ) can be replaced by 3Ca, because 2H3 has a total 
valence of 6 and so has 3Ca. 

2 H 3 P0 4 + 3 Ca(OH) 2 = Ca 3 (P0 4 ) 2 + 6H 2 0. 

3Ca atoms replace the 2H3 and form Ca 3 (P0 4 ) 2 , a bal- 
anced compound, because P0 4 is a radical having a valence 
of 3, and if taken twice its total valence is 6, with which 
3 Ca atoms can combine. The remaining H and O atoms 
form 6H 2 0. 

i49. Impossible Reactions. — Not all chemical com- 
pounds when brought together give a chemical reaction. 
Whether or not a reaction takes place can be determined 
only after a careful study of the elements and their prop- 
erties ; this often involves a more exhaustive knowledge 
of chemistry than can be obtained from an elementary 
study of the subject. 

In the case of BaS0 4 + 2HCI, no reaction can take 
place, although an apparently correct reaction can be 
written : 

BaS0 4 + 2HCI = BaCl 2 + H 2 S0 4 . 
This is because BaS0 4 and HC1 are the products of the 
reaction 

BaCl 2 + H 2 S0 4 = BaS0 4 + 2HCI. 
In the equations given at the end of this chapter a reac- 
tion takes place in each case. 



124 AGRICULTURAL CHEMISTRY 

150. A Knowledge of Reacting Compounds and Prod- 
ucts Necessary. —In order that the writing of chemical 
equations may become more than a mere mechanical op- 
eration, the student should study the character and prop- 
erties of the compounds used and of the products formed. 
If one of the compounds is an acid and the other a base, 
the subject of neutralization is illustrated. If one of the 
compounds is an acid and the other a metal, the re- 
placement of the H of the acid occurs. Should one of 
the compounds be an acid and the other a salt, an equiva- 
lent amount of the H is replaced by the metal or basic 
element of the salt. Other principles and laws should 
be observed by the student in writing equations. The 
character of the compounds, as acid, base, or salt, with 
their names, forms a part of equation work, which is an 
essential feature of elementary chemistry. 

151. Equations for Class Room Work. — The student 
should write the following equations : 

1. CaCl 2 + Na 2 C0 3 = 

2. CaCl 2 + Na 2 S0 4 = 

3. Ca(OH) 2 + H 2 S0 4 = 

4. CaC0 3 + HCl = 

5. MgC0 3 + HCl = 

6. KN0 3 + H 2 S0 4 = 

. 7. CaCl 2 + Na 8 (POJ = 

8. Pb(N0 3 ) 2 + 2HCI = 

9. A1C1 S + NH 4 OH = 

10. Ba(OH) 2 + H 2 S0 4 = 

11. BaCl 2 + H 2 S0 4 = 

12. Pb(NO s ) 2 + H 2 S0 4 = 



WRITING EQUATIONS 1 25 

13. Na 2 C0 3 + H 2 S0 4 = 

14. Na 3 P0 4 + H 2 S0 4 = 

15. Ca(OH) 2 + Na 2 S0 4 = 

16. Fe(OH) 3 + H 2 S0 4 = 

17. (NH 4 ) 2 S0 4 +Ca(OH) 2 = 

18. NH 4 N0 3 + H 2 S0 4 = 

19. (NHJ 2 C0 3 + HC1 = 

20. NH 4 C1 + H 2 S0 4 = 

21. NH 4 Cl + Ca(OH) 2 = 

22. NH 4 C1 + NaOH = 

23. NH 4 Cl+Ba(OH) 2 = 

24. NH 4 N0 3 + Ca(OH) 2 =: 

25. NH 4 OH-f-HCl = 

26. NH 4 N0 3 + KOH = 

27. FeCl 2 + NaOH = 

28. FeCl 2 + NH 4 OH = 

29. AgCl + NaOH = 

30. Na 2 CO s + Ba(OH) 2 = 

31. Na 2 C0 3 + HCl = 

32. NaOH + FeCl 2 = 

33. AgN0 3 + NaCl = 

34. AgN0 3 + HCl = 

35- Ca 3 (P0 4 ) 2 + 3 H 2 S0 4 = 
36. CaC0 3 + heat = 
37- CaO + C0 2 = 
38. Ca(OH) 2 + C0 2 = 
39- K + H 2 = 

40. A1K(S0 4 ) 2 + 4 K0H = 

41. A1NH 4 (S0 4 ) 2 + NH 4 0H- 

42. CaCl 2 + (NH 4 ) 2 CO s = 



126 AGRICULTURAL CHEMISTRY 

43. CaCl 2 + H 2 S0 4 = 

44. Na 2 Si0 3 + HC1 = 

45. CaSi0 3 + Na 2 C0 3 = 

46. C + CuO = 

47. 3 Cu + 8HN0 3 = 

48. C 6 H 10 O 5 +i2O = 

49. A1C1, + H 3 PO, = 

50. AICI3 + NH 4 OH = 



CHAPTER XVIII 
Potassium, Sodium, and Their Compounds 

152. Occurrence of Potassium.— Potassium is found in 
nature largely in combination with silicon and other ele- 
ments, forming silicates, which undergo slow disintegra- 
tion with liberation of potassium salts which become food 
for plants. Potassium is present in the ash of all plants 
and food materials and is one of tUe elements required by 
crops. In some ' ' alkali' ' soils, small amounts are found 
in the form of potassium salts. Deposits of various 
double salts of potassium, supposed to have been formed 
by crystallization from sea-water, are found at Stassfurt in 
Prussia, and are commonly known as Stassfurt salts. These 
are the chief source of the potassium compounds, some of 
which are extensively used in the preparation of fertilizer. 

The element potassium is most typical of all the base 
elements as a class. It is never found in nature in 
a free state, but always in combination with other ele- 
ments from which it is separated with difficulty. It is a 
light substance with a metallic luster, and in the labora- 
tory is kept out of contact with air and water, with which 
it readily reacts. 

153. Potassium Hydroxid. — This is a strong basic 
compound extensively used in the laboratory and in 
manufacturing operations. It is prepared by treating 
K 2 C0 3 with Ca(OH) 2 , the reaction being K 2 C0 3 + 
Ca(OH) a = CaC0 3 + 2KOH. CaC0 3 is insoluble and 
can be separated by filtering from KOH which is soluble. 



AGRICULTURAL CHEMISTRY 




KOH, commonly called caustic potash, is a white, brittle 
substance which readily absorbs moisture and carbon 
dioxid from the air. 

Experiment 26. — Preparation of KOH. Dissolve 5 grams potas- 
sium carbonate, K 2 C0 3 , in an evaporating dish containing 15 cc. of 
water. Add a mixture of 3 grams Ba(OH) 2 
and 10 cc. of water. Heat on the sand-bath 
for five minutes. Filter off the solution. Ob- 
serve the precipitate. Evaporate some of the 
solution to dryness in the evaporator. 

Questions. ( 1 ) Write the reaction which takes 
place between K 2 C0 3 and Ba(OH) 2 . (2) What 
is the insoluble white material left on the filter- 
paper? (3) Is the KOH soluble or insoluble? 
^4) What other material could be used in place 
£T of Ba(OH) 2 ? (5) If Na 2 CO s were used instead 
Fig. 54 , —preparation of K 2 C0 3 , what product would be formed ? Write 
of koh. the reac tion. (6) What reaction does K 2 C0 3 

give with litmus paper? (7) What reaction does NaOH give? 
(8) What are some of the uses made of KOH? (9) What would 
result if the KOH in the evaporator were left exposed to the air 
for a day or so ? 

154. Potassium Nitrate. — This salt is found in small 
amounts in fertile soils where conditions have been favor- 
able for nitrification processes (see Section 92). It is 
extensively used in the arts, and is prepared from 
sodium nitrate deposits which occur as natural products 
known as Chile saltpeter. It is an oxidizing agent and 
is one of the ingredients of gunpowder which is a mix- 
ture of sulfur, carbon and potassium nitrate. Potas- 
sium nitrate, in small amounts, is occasionally used for 
the preservation of meats. 



POTASSIUM, SODIUM, ETC. 1 29 

155- Potassium Carbonate. — When wood ashes are 
leached, potassium carbonate is the chief alkaline salt 
extracted, and this product is called potash which, by 
the removal of impurities, furnishes pure K 2 C0 3 . Potas- 
sium carbonate is prepared from the chlorid in the same 
way that sodium carbonate is prepared from its chlorid as 
explained in Section 162. 

156. Potassium Chlorate is prepared by the action of 
chlorin gas upon potassium hydrate. It is used in the 
laboratory as an oxidizing agent, and for the preparation 
of oxygen. It is one of the ingredients of safety matches. 

157. Potassium Sulfate is found in nature in the form 
of double salts, in the Stassfurt deposits and elsewhere. 
It is employed in the preparation of alum and other com- 
pounds. There are two sulfates of potassium : primary on 
acid potassium sulfate, KHS0 4 , and secondary or normal 
potassium sulfate, K.SO^. 

158. Miscellaneous Potassium Salts. — Potassium 
forms a large number of salts, as KC1, KBr, KF, KI, 
KCN, K 2 0, K 2 S, KN0 2 , many of which are very valuable 
in medicine, in the arts as photography, and in the labora- 
tory for the preparation of other compounds. The salts 
of potassium vary in chemical and physical properties 
according to the acid elements or radicals with which the 
potassium is combined. All of the common salts of 
potassium, except the double silicates, are soluble in 
water. 

159. Occurrence of Sodium. — Sodium and potassium 
are very much alike in general properties, and form analo- 



1 3O AGRICULTURAL CHEMISTRY 

gous salts and compounds. Sodium is not as strong a 
type of basic element as is potassium and can be sepa- 
rated from its compounds more readily, although it is not 
easily replaced by other elements or by simple chemical 
forces. Sodium and its compounds are less expensive 
than potassium and its compounds. In industrial opera- 
tions, sodium salts are more extensively used, but to the 
agricultural student, potassium is of greater importance 
because sodium takes little or no part in plant nutrition. 
In animal life, however, sodium chlorid plays an import- 
ant r61e. Sodium is never found in nature in a free state, 
sodium chlorid being one of the most abundant of its 
salts. Sodium is also found as silicates and in small 
amounts in other forms. 

160. Sodium Chlorid. — Extensive deposits of this salt 
are found in nature ; in some places it is mined, the prod- 
uct being known as rock salt. It is present in sea-water 
in large amounts from which it is occasionally obtained 
in an impure form along with a large number of other 
salts. When pure, sodium chlorid forms colorless, trans- 
parent cubes. A large amount of commercial salt is ob- 
tained by the evaporation of water from salt springs. In 
some localities, water is forced into and through deposits 
of salt which it dissolves and is then pumped out and 
evaporated to dryness. Sodium chlorid is extensively 
used for the preparation of sodium and other compounds 
as hydrochloric acid. It is not found to any appreciable 
extent in ordinary agricultural plants, but in some alkali 
plants there are quite large amounts. When sodium 
chlorid contains impurities, as calcium chlorid and lime 



POTASSIUM, SODIUM, ETC. 131 

salts, the material readily absorbs moisture from the air 
while other compounds cause it to form lumps and hard 
cakes. Hence a salt which readily absorbs moisture or 
forms hard lumps is not a pure one. Sodium chlorid 
takes but little or no part in plant life but is necessary 
for animal life. 

161. Sodium Nitrate. — Extensive deposits of sodium 
nitrate are found in Peru, Chile, and other South Ameri- 
can countries. It is commonly called Chile saltpeter. 
As stated in Section 154, it is extensively used for the 
preparation of potassium nitrate and in the manufacture 
of nitric acid and commercial fertilizers. Sodium nitrate 
is commercially and agriculturally an important product. 
The value of nitrogen in fertilizers is usually based upon 
its selling price. Small amounts of this salt formed by 
the process of nitrification are found in soils of high fer- 
tility. Because of its solubility, however, sodium nitrate 
never accumulates in soils. 

162. Sodium Carbonate. — Commercially, this salt is 
known as soda and is one of the most useful chemicals 
manufactured. It is extensively used in the making of 
soap and glass, and in other commercial operations. It 
is prepared by two processes, one known as the L,e Blanc 
process, and the other as the ammonia or Solvay process. 
By the Le Blanc process, it is prepared from sodium 
chlorid treated with sulfuric acid which produces Na 2 S0 4 . 

2NaCl + H 2 S0 4 = Na 2 S0 4 + 2HCI. 
The sodium sulfate is heated with charcoal which pro- 
duces sodium sulfid. 

Na 2 SO, + 2C = Na 2 S + 2 CO,. 



132 AGRICULTURAL CHEMISTRY 

When heated with calcium carbonate, sodium sulfid forms 
sodium carbonate and calcium sulfid, the latter product 
being insoluble in water while sodium carbonate is solu- 
ble in water, and hence is readily separated by filtration. 
The process of manufacture usually consists in mixing 
coal and calcium carbonate with sodium sulfate, the prod- 
uct being known as crude soda which is refined and from 
which calcined and crystallized soda are obtained. 

In the Solvay process, (NH 4 ) 2 C0 3 is employed, which 
forms, with sodium chlorid, HNaC0 3 which when heated 
yields Na 2 C0 3 , C0 2 and H 2 0. 

163. Sodium Hydroxid. — This base is prepared in the 
same way as KOH ; Na 2 C0 3 being used in place of 
K 2 C0 3 . NaOH is extensively used in the manufacture 
of soaps. 

164. Sodium Phosphates. — Sodium forms three phos- 
phates : primary sodium phosphate, secondary sodium 
phosphate, NaHP0 4 , and tertiary or normal sodium phos- 
phate, Na 3 P0 4 . Phosphates of soda are not found to any 
appreciable extent in soils because phosphoric acid forms, 
with iron, alumina and calcium which are always present, 
insoluble compounds. 

165. fliscellaneous Sodium Salts. — L,ike potassium, 
sodium forms a large number of salts as Na 2 S0 4 , NaHS0 4 , 
NaBr, NaCN, Na 2 S and Na 2 0. Sodium compounds are 
all soluble except the silicates and a few of the more com- 
plex salts. 

As previously stated, salts of sodium are similar to the 
corresponding salts of potassium. The sodium com- 



POTASSIUM, SODIUM, ETC. 



133 



pounds are among the most useful and important com- 
pounds found in nature. 

Experiment 27. — Fill a cylinder about two-thirds full of water, 
and place upon the surface of the water a piece of Na about half as 
large as a pea, using forceps for the 
purpose. If there is no small piece 
of Na in the bottle, one may be cut 
by means of a knife without re- 
moving the Na from the naphtha 
which surrounds it. Observe the 
result when the Na is placed upon 
the water. The apparatus can be 
arranged and the escaping hydro- 
gen collected as shown in Fig. 55. 
(The test-tube should be filled with 
water and the Na wrapped in a 
piece of filter-paper.) 

Questions. (1) Give the reaction 
which takes place between the Na 
and the H 2 0. (2) What gas is lib- 
erated ? ( 3 ) What becomes of the 
Na in the experiment? (4) Is this 
product soluble or insoluble? (5) 
Test the liquid in the cylinder with 
litmus paper and observe the result. 
(6) Is Na a light or heavy metal ifflffiP 
Why? (7) Is it active or inert? (8) 
Why is Na always kept in a bottle 
containing naphtha or kerosene? (9) Since Na is found in nature 
and its compounds are present largely in sea-water, why does not 
this element, Na, decompose sea-water as it did the water in this 
experiment. 




F'&- 55- — Decomposition of water 
by the use of sodium. 



CHAPTER XIX 
Calcium, Magnesium, and Their Compounds 

166. Occurrence of Calcium. — This element is found 
widely distributed in nature in the form of calcium car- 
bonate, CaC0 3 , calcium phosphate, Ca 3 (POJ 2 , and calcium 
sulfate, CaS0 4 , and is a yellowish metal which readily 
oxidizes and decomposes water. It enters into the com- 
position of both plant and animal bodies and takes an 
important part in life processes. Its compounds are use- 
ful in the industries, lime, cement, and mortar being some 
of the forms in which it is employed. Calcium is not 
easily separated from its compounds. 

167. Calcium Carbonate. — This compound, in the form 

of limestone 
and marble, is 
found quite 
extensively. 
It is soluble to 
a slight ex- 
tent in water 
charged with 
carbon dioxid, 
and hence 
many waters, 
as stated in 
Section 65, 




mi 

Fig. 56. Section of lime kiln. 

owe their hardness to its presence. Calcium carbonate is 
used principally for the preparation of quicklime, in the 



CALCIUM, MAGNESIUM, ETC. 



135 



manufacture of glass and in the refining of some of the 
metals where it is employed as a flux. 

168. Calcium Oxid. — When calcium carbonate is sub- 
jected to heat, as in lime kilns or specially constructed 
furnaces, the carbon dioxid is separated and the oxid ob- 
tained. Layers of limestone and wood are placed alter- 
nately in the lime kiln, as shown in Fig. 56; the combus- 
tion of the wood furnishes the necessary heat for the de- 
composition of the carbonate. Calcium oxid or quick- 
lime readily combines with both the carbon dioxid and 
moisture of the air, forming air-slaked lime. During this 
process of slaking, there is a material increase in volume 
often resulting in the bursting of the barrels in which the 
lime is stored. Calcium oxid is used for the preparation 
of calcium hydroxid and mortar. 

169. Calcium Hydroxid. — When water is added to cal- 
cium oxid or quicklime, the material 
undergoes the slaking process and cal- 
cium hydroxid, Ca(OH) 2 , is produced. 

CaO + H 2 0= Ca(OH) 2 . 
Calcium hydroxid or slaked lime 
readily absorbs carbon dioxid from 
the air and forms calcium carbonate. /?( 
Ca(OH) 2 is somewhat soluble in Vyf 
water, forming what is commonly / 
called lime water. When carbon 
dioxid is passed into lime water, the 
solution becomes turbid, due to the Fig. 57. 

formation of CaCO,. This reaction furnishes a means 




136 



AGRICULTURAL CHEMISTRY 



of testing for carbon dioxid. If a small amount of 
any material supposed to contain carbonates is placed 
in a test-tube along with a little water, and then a small 
glass tube or loop-tube containing a few drops of lime 
water is inserted in the test-tube, after the gas is liberated 
by hydrochloric acid, the drop of lime water becomes 
turbid, due to the formation of CaC0 3 (see Fig. 57). 

170. Calcium Sulfate. — Deposits of this salt known as 
gypsum, CaS0 4 .2H 2 0, are found abundantly in some lo- 
calities. Gypsum or land plaster is used as a fertilizer 
and also for the preparation of plaster of Paris. The 
"setting" of plaster of Paris is due to the fact that when 
the water of crystallization is expelled, the substance is 
again capable of taking up water, expanding, and form- 
ing a hard mass. 

171. Calcium Chlorid. — This salt is not found in nature 
to any appreciable extent. It is employed in the labora- 
tory in desiccators and for the drying of gases. 

172. Bleaching=Powder. — This mate- 
rial is made by passing chlorin into a 
solution of lime water. The chlorin is 
held in chemical combination, forming 
calcium hypochlorite, Ca(C10) 2 , which 
readily gives up its chlorin and is exten- 
sively used for bleaching and disinfect- 
ing purposes as explained in Section 89. 

173. Calcium Phosphate. — Deposits 
Fig. 58. Apatite rock. f this material are found in nature in 
various physical forms as soft phosphate, and in crystalline 




CALCIUM, MAGNESIUM, ETC. 137 

form, as apatite rock, see Fig. 58. Calcium phosphate is 
extensively used for the preparation of commercial fer- 
tilizers as explained in Section 109. 

174. Mortar. — When quicklime is slaked and mixed 
with sand, it forms at first a mechanical mixture. When 
it is placed upon the walls of buildings, a chemical change, 
known as the hardening or setting process, takes place. 
When this change occurs, the moisture is expelled and 
the carbon dioxid of the air changes the calcium hydroxid 
to calcium carbonate. In the slaking of lime and setting 
of mortar, the following reactions take place : 

( 1 ) CaO + H 2 = Ca(OH) 2 . 

(2) Ca(OH) 2 + C0 2 =CaC0 3 . 

When magnesium carbonate and aluminum silicate are 
present, forming a part of the composition of the original 
lime rock, hydraulic cement is produced which has the 
property of setting under water. 

Experiment 28. — Testing quality of lime. Place about 40 
grams of lime, CaO, in an evaporating dish and moisten with water 
warmed to about 35 ° C. Note the reaction. Good lime readily 
undergoes the slaking process. Place some of the slaked lime in 
a bottle, add about 100 cc. of. distilled water, shake vigorously and 
leave the lime in contact with the water for four hours or longer, 
then filter some of the solution of lime water, and test it by 
forcing respired air through it as explained in Experiment 24. 

Place about one-half gram of the slaked lime in a test-tube, add 
10 cc. of water and then a few drops of HC1. When action ceases, 
add more HC1, a little at a time, and heat. The material which 
fails to dissolve usually consists of insoluble silica and clay. Lime 
of a high degree of purity contains less than 10 per cent, of acid-in- 
soluble impurities. 

Questions. (1) Was any heat evolved when the lime was 



138 AGRICULTURAL CHEMISTRY 

slaked ? Why ? ( 2 ) Did any noticeable change take place in vol- 
ume during slaking ? (3) What is lime water? (4) What is the 
object of forcing respired air through the lime water of the test- 
tube? (5) Write the reaction which took place. (6) Write the 
reaction when HC1 was added to Ca(OH) 2 . 

175. Glass. — Glass is a double silicate of calcium and 
sodium, produced by fusing pure sand, sodium carbonate 
and lime. When potassium carbonate is substituted for 
the sodium salt, Bohemian or hard glass is prepared. 
Other kinds and varieties of glass are made by intro- 
ducing other substances and giving different mechanical 
treatment to the material during its preparation. 

i76. Occurrence of Magnesia.— This element does not 
occur as extensively in nature as calcium which it resem- 
bles in many respects. It is found associated mainly 
with calcium in the mineral dolomite, a double carbonate 
of calcium and magnesium. Magnesium is separated 
from its compounds more readily than calcium. It is 
found in both plant and animal substances as is calcium. 
In some plants and in some parts of the plant, as in the 
seeds of grains, it is found more abundantly than calcium. 
It is generally considered one of the essential elements of 
plant food. The compounds of magnesium resemble 
those of calcium in many respects, but differ materially 
from the calcium salts in both chemical and physical 
properties. 

177. riagnesium Salts. — Magnesium carbonate and 
magnesium sulfate (Kpsom's salt) are among the most 
common of the magnesium compounds. Magnesium 
chlorid, MgCl 2 , and MgS0 4 are found as double salts in 



CALCIUM, MAGNESIUM, ETC. I39 

the Stassfurt deposits. Magnesium oxid is obtained by 
the combustion of magnesium. Magnesium also forms 
other compounds as nitrates, phosphates, silicates, etc. 

Experiment 2g. — Hold a piece of magnesium ribbon about an 
inch long in the forceps and apply a lighted match to the ribbon. 
Examine the product. 

Questions. ( 1 ) What are some of the chemical properties of 
the element as observed from this experiment ? (2) What product 
was formed? Write the reaction. (3) Which would weigh more, 
the original magnesium ribbon or the white powder obtained from 
its combustion ? Why? (4) Why does magnesium produce such 
an intense light ? 



CHAPTER XX 
Iron, Aluminum, and Their Compounds 

178. Occurrence of Iron. — Iron is found in nature 
mainly in the form of its oxids, hematite, Fe 2 3 , and 
magnetite, Fe 3 4 . It also occurs in the form of carbonate, 
FeC0 3 , pyrite, FeS 2 , and brown iron ore or basic hydroxid. 
It is found in the soil in combination with silicon and 
other elements, forming double silicates. It enters into 
the composition of all plant and animal bodies and takes 
an essential part in plant growth and animal life. Some 
waters contain carbonate of iron which, like calcium 
carbonate, is soluble in the presence of carbon dioxid ; 
upon exposure to the air, the iron is precipitated as hy- 
droxid, forming a brown deposit. Iron takes an im- 
portant part in industrial operations and its chemistry 
has been more extensively studied than that of any other 
element. 

179. Reduction of Iron Ores. — Only iron ores of a high 
degree of purity are ready, as mined, for the blast-furnace. 
Magnetic iron ore is concentrated and separated from its 
impurities by magnetic concentrators. The blast-fur- 
nace used for the production of cast iron is constructed 
of brick and is shown in Fig. 59. Ore, coke, and flux, 
usually limestone, are mixed in the right proportion and 
introduced into the top of the furnace. The flux is used 
to separate the impurities, forming a fusible slag which 
is largely calcium silicate. Hot air is forced into the 
furnace by means of blowing engines, through tuyeres. 



IRON, ALUMINUM, ETC. 



141 




Fig. 59. Blast-furuace (after Hart). 



142 AGRICULTURAL CHEMISTRY 

The carbon dioxid produced first is reduced to carbon 
monoxid which passes over the heated ore in the upper 
part of the furnace, and is the main reducing agent of the 
blast-furnace. The carbon monoxid given off at the top 
of the furnace is collected and used for heating the blast. 
The furnace is constructed so as to utilize the heat to the 
best advantage and so that the blast can act efficiently. 
The slag which carries a large portion of the impurities 
of the ore, being lighter than the molten iron, collects on 
the surface and is removed from time to time. The 
molten iron is run off from the bottom of the furnace 
into molds ; iron that is produced in this way is known 
as pig iron. It contains a number of impurities as phos- 
phorus, carbon, silicon and sulfur. 

180. Wrought Iron. — Wrought iron is produced from 
cast iron by two processes: (i) the puddling process 
which consists of oxidizing the impurities by means of a 
blast of hot air which is passed over or blown throuhg 
the iron, this is known as the Bessemer process ; 
and (2) the cementation process by which the cast 
iron is mixed with iron ores reasonably pure and heated 
to a high temperature so that the oxygen of the ores may 
oxidize the carbon, phosphorus and sulfur of the cast 
iron. Wrought iron is the purest commercial form of 
iron. It usually contains about 0.5 per cent, of carbon, 
and melts at about 2000 ° C. The nature of the 
impurities determines the character of both wrought iron 
and steel, as any increase in the amount of carbon de- 
creases its malleability and other desirable properties. 

181. Steel. — This form of iron contains less carbon 



IRON, ALUMINUM, ETC. 



H3 




144 AGRICULTURAL CHEMISTRY 

than cast iron, but more than wrought iron. It is pre- 
pared by oxidizing the impurities of iron by means of a 
blast of hot air. This is accomplished by heating the 
cast iron in converters and then forcing through it a blast 
of hot air which oxidizes the larger portion of the im- 
purities. By adding cast iron, steel containing almost 
any desired amount of carbon can be obtained. Iron and 
steel wire are made by drawing rods through hardened 
steel plates, the material being properly tempered during 
the operation. The thin coat of oxid formed on the sur- 
face is removed by dipping the wire into a bath of dilute 
sulfuric acid. 

182. Rusting of Iron. — Iron in all of its forms readily 
undergoes oxidation and rusting, due to the joint action 
of oxygen and water which results in the production of 
a basic oxid of iron. When the surface of iron is pro- 
tected, as by painting, oxidation and rusting are pre- 
vented. When iron is heated to its kindling temperature, 
it readily oxidizes as in Experiment 1. In the welding 
of iron, oxidation is prevented as far as possible by ma- 
nipulation and occasionally by the use of materials, as 
borax, to remove the thin coating of oxid. Iron is read- 
ily acted upon by all acids, forming a large number of 
salts. 

183. Iron Compounds. — Iron forms two series of salts : 
ferrous and ferric. Ferrous sulfate, FeS0 4 , commonly 
called copperas, is used most extensively of any of the 
iron salts especially for the dyeing of cloth, and to some 
extent as a disinfectant. 

Experiment 30. — Dissolve 0.5 gram of ferrous sulfate in 20 cc. of 



IRON, ALUMINUM, ETC. 145 

water. Filter if the solution is not clear, and divide the filtrate 
into two portions. To the first portion, add a few drops of ammo- 
nium hydroxid until a precipitate is obtained. To the second portion, 
add about 5 drops of strong nitric acid. Heat to boiling ; when 
cool, add ammonia to neutralize the acid and precipitate the iron. 
The nitric acid oxidizes the iron and changes it from the ferrous 
to the ferric condition. Compare the two precipitates. 

Questions. (1) What was formed when NH 4 OH was added to 
FeS0 4 ? Write the reaction. (2) Give the color and other physical 
properties. (3) What change did the HNO s produce ? (4") What 
change did you observe in the color of the solution during the 
boiling? (5) What was produced when NH 4 OH was added to 
Fe(OH) 3 ? Write the reaction. (6) Give the color and some of 
the physical properties. (7) How does this last precipitate differ 
from the first one obtained ? 

Experiment jz. — Dissolve 1 gram tannic acid in 25 cc. of hot 
water. Dip a piece of cotton cloth into this solution. Dry the 
cloth and then dip it into a solution of ferrous sulfate (1 gram per 
25 cc. of water). After the cloth has dried, see if the color can be 
removed by washing. Add 5 cc. of ferrous sulfate solution to 5 cc. 
of tannic acid solution. Observe the result. The FeS0 4 forms, 
with the tannic acid, iron tannate. 

Questions. (1) Would the FeS0 4 alone give the same color 
to the cloth ? Why ? ( 2 ) Was the color produced a permanent 
one? (3) Tea contains tannic acid ; why does tea prepared in an 
iron kettle give a black infusion ? (4) What was produced when 
the solution of FeS0 4 was added to the tannic acid ? 

184. Occurrence of Aluminum. — Aluminum is a gray- 
ish white metal much lighter than iron and of greater 
tensile strength and is found mainly as one of the constitu- 
ents of clay that is formed from the disintegration of 
feldspar, a double silicate of potassium and aluminum. 
It is also found in other combinations, as in mica and 
cryolite, and is present in nearly all soils and in small 



146 AGRICULTURAL CHEMISTRY 

amounts is found in plant substances although it takes no 
part as plant food. Aluminum is not easily isolated from 
its compounds. It can be pioduced by treatment of its 
chlorid with sodium but is now quite extensively pre- 
pared by electrolysis. When pure, it is not as readily 
oxidized or acted upon by acids as is iron. Aluminum 
forms a large number of compounds and also alloys with 
many of the metals. 

185. Alums. — In industrial operations, alum is used 
the most extensively of any of the compounds of alumi- 
num. An alum is a double sulfate of aluminum. It has 
the general composition of MAl(S0 4 ) 2 i2H 2 in which M 
represents any bivalent metal as potassium. The Al can 
also be replaced by a trivalent element. Alum is exten- 
sively used in the tanning of leather, manufacture of 
paper, and in the coloring of cloth as the basis of the 
mordant or material for making the dye permanent. 
Alum is also used occasionally in the preparation of 
baking-powders. 

Experiment 32. — Add a few drops of alum solution to a test-tube 
containing 5 cc. of water, and then add a few drops of tincture of 
logwood and 2 cc. (NH 4 ) 2 CO g . Observe the result. Mix about 
2 grams of flour in a dish with water containing a few drops of 
alum. Add a few drops of logwood and the same amount of am- 
monium carbonate solution ; mix well, and observe the result. Re- 
peat the test, using a baking-powder, and test for the presence or 
absence of alum. In the presence of alum, a blue color is always 
obtained with tincture of logwood and ammonium carbonate solu- , 
tion. 

Experiment ss. — To a solution of egg albumin, add a few drops 
of alum solution and observe the result. 



IRON, ALUMINUM, ETC. 147 

Questions. (1) Does the alum cause a precipitate ? (2) Of what 
is the precipitate composed ? (3) How would alum act in the di- 
gestive tract in the presence of soluble albuminous compounds? 
(4) Why is alum an undesirable ingredient in baking-powders and 
foods. 

186. Pottery. — Pure clay or kaolin is used for the 
manufacture of the best grades of porcelain and pottery. 
The plastic clay is modeled into the desired form and 
then dipped into a bath containing feldspar and other 
materials which, when fused, form the glaze. Ordinary 
earthenware is made from impure clay which contains 
compounds of iron and other elements. Brick and tile 
are also made from clay, the physical properties, as color, 
hardness, weathering properties, etc., depending upon 
the amounts of iron, lime, magnesia, and alkalies present- 
As ordinarily found in the soil, clay is mechanically asso- 
ciated with a large number of other substances, many of 
which contain the elements essential to plant life as po- 
tassium and calcium. Pure clay itself contains no plant 
food, but clay soils are usually among the most fertile 
because, along with the disintegration of feldspar and 
other rocks, various minerals that impart fertility are 
made available and are associated with the clay. 



CHAPTER XXI 

Copper, Zinc, Lead, Tin, Arsenic, Mercury, and 

Their Compounds and Alloys. 

187. Commercial Importance. — The compounds of 
copper, zinc, lead, tin, and arsenic, while they do not 
enter into the composition of either plant or animal 
bodies, are of value in agriculture because of their pres- 
ence in many useful materials. 

188. Occurrence of Copper and Its Hetallurgy. — This 
element is found in the free state and also in combination 
with oxygen as CuO and Cu 2 0, with sulfur as Cu 2 S, and 
with iron and sulfur as copper pyrite, Cu 2 S.Fe 2 S 3 . The 
ores of copper are first roasted, and if iron is present in 
large amounts, it is removed as a silicate. The "matte," 
as it is called, thus produced is subjected to further re- 
fining. Copper is also produced by electrolysis. 

189. Copper Sulfate. — This salt is used the most ex- 
tensively of any of the copper compounds and is produced 
by the action of sulfuric acid upon either metallic copper 
or its sulfid. It crystallizes with 5 molecules of water of 
crystallization. It is commonly called blue vitriol, and 
is extensively used in the preparation of pigments, for the 
preservation of wood, for copper-plating and for the 
treatment of fungus diseases in plants as in the Bordeaux 
mixture where it is the principal ingredient. 

Experiment 34. — Dissolve 6.2 grams of copper sulfate and 3.50 
grams of sodium potassium tartrate in 100 cc. of water. Dissolve 
a small amount of glucose (0.1 gram) in 5 cc. of water, add 5 cc. 



COPPER, ZINC, LEAD, ETC. 149 

of alkaline copper sulfate solution and heat to boiling. Observe 
the brown precipitate of Cu 2 0. The amount of Cu 2 produced is 
proportional to the amount of glucose present and when the work 
is carefully done and the copper weighed or determined by other 
means, the percentage amount of glucose in a material can be de- 
termined. A hot alkaline solution of copper sulfate is reduced to 
Cu 2 in the presence of glucose, and a few other organic com- 
pounds. 

190. Bordeaux Mixture. — In this preparation, the 
copper is present as an insoluble hydroxid. To prepare 
the Bordeaux mixture 12.5 pounds of copper sulfate 
are dissolved in about 2 gallons of hot water; 3.5 pounds 
of lime are slaked in about 2 gallons of water, and 
strained into a barrel through a coarse cloth to remove 
any large pieces. The solution of copper sulfate is then 
poured into the barrel and well stirred. The reaction 
which takes place is 

Ca(OH) 2 + CuSO, = Cu(OH) 2 + CaSO,. 
In the preparation of Bordeaux mixture, it is the aim 
to use just a sufficient amount of lime to combine with 
all of the copper. 

191. Occurrence of Zinc. — This metal is found in nature 
mainly as zinc carbonate, ZnC0 3 , and to a less extent as 
the sulfid. Small amounts are found in other forms. 
Zinc is separated from its ores by roasting with char- 
coal which, volatilizes and it is then collected as zinc 
dust. It is then purified and prepared for various pur- 
poses. 

192. Compounds of Zinc. — Zinc forms a large number 
of compounds as ZnCl 2 , Zn(OH) 2 , ZnS, and ZnS0 4 . 



150 AGRICULTURAL CHEMISTRY 

Some of the zinc salts are used in the preparation of 
paints, while the metal itself is used in many ways as in 
the preparation of alloys, solder, and galvanized iron. 

193. Galvanized Iron. — Iron is galvanized by being cov- 
ered with a layer of zinc. Galvanized iron is extensively 
used for water pipes because it does not rust so readily as 
ordinary iron. When heated, however, the zinc coating 
of the galvanized iron is removed. 

194. Occurrence of Tin.— Tin is found in nature largely 
in the form of the oxid, Sn0 2 , and, to a less extent, in 
combination with other metals. The oxid is heated in a 
furnace with charcoal, and the molten tin cast into bars. 

195. Tin Salts. — Tin forms two series of salts, stan- 
nous and stannic. In the former, the element is bivalent, 
and in the latter, it is tetravalent. Stannous and stannic 
chlorid, the sulfid, oxid and hydroxid are among the 
more common tin salts. They are used in the arts in 
various ways as pigments and as mordants in the coloring 
of cloth. Tin forms a number of alloys and is extensively 
used for roofing and other purposes. Ordinary tinware 
is simply iron-coated with a layer of tin. 

196. Occurrence of Lead. — Lead is found principally 
in the form of sulfid (galena). It is also found in combi- 
nation with silver and other metals, and, in the process 
of refining of silver, is separated as a by-product. 

197. Oxids of Lead. — There are four oxids of lead, 
namely : lead monoxid, PbO, lead peroxid, Pb0 2 , lead 
suboxid, Pb 2 0, and lead sesquioxid, Pb 2 3 . The sub- 



COPPER, ZINC, LEAD, ETC. 151 

oxid, Pb 2 0, is produced when lead is exposed to the air; 
in a pure condition, it is a black powder. Lead oxid, 
PbO, is a yellow powder which, if heated, produces 
litharge, a yellowish red material. This substance is ob- 
tained largely in the separation of lead from silver. Lead 
peroxid, Pb0 2 , is an oxidizing agent, and in some respects 
resembles manganese dioxid. Red led or minium, Pb 3 4 , 
is produced by heating lead oxid, and is used as a pig- 
ment. 

198. Lead Carbonates. — The normal carbonate, PbC0 3 , 
is occasionally found in nature. The basic carbonate, 
Pb(OH) 3 .3PbC0 3 , is common white lead, which is exten- 
sively used as a pigment. It is produced by different 
methods from litharge and other compounds of lead, as 
well as by treatment of the metal itself. 

199. Lead Salts. — Lead nitrate, Pb(N0 3 ) 2 , is produced 
by the action of nitric acid on lead ; and lead sulfate, by 
the action of a sulfate upon a soluble lead salt. Lead 
chlorid, PbCl,, is precipitated whenever a chlorid or hy- 
drochloric acid is added to a solution containing a lead 
salt. The salts of lead are more insoluble than those of 
many other metals. 

200. Uses of Lead. — Lead is used for making water 
pipes, for lining tanks, particularly those in which sul- 
furic acid is stored, in the preparation of solder, and in 
many alloys. Lead is insoluble in most waters although 
the salts and organic matter in some waters may cause a 
sufficient amount to dissolve to render the use of lead 
pipes objectionable from a sanitary point of view. 



152 AGRICULTURAL CHEMISTRY 

201. Occurrence of Arsenic. — This element occurs in 
the free state to a limited extent, but usually in combina- 
tion with other elements, as oxygen, iron, and sulfur. 
In some of its properties, arsenic resembles phosphorus, 
and forms similar compounds, although arsenic has 
weaker acid properties than phosphorus. It forms a large 
number of compounds, among which are the arsenates, 
and arsenites which are salts of arsenic and arsenious 
acids. In the presence of a strong base element, arsenic 
deports itself as an acid while, in the presence of a strong 
acid element, it exhibits basic properties. Other ele- 
ments, particularly antimony and bismuth, and to a less 
extent aluminum, have this same property of acting both 
as an acid- and base- forming element. Some of the com- 
pounds of arsenic are extensively used as pigments and 
insecticides. 

202. Paris Green. — Pare Paris green is an aceto-arse- 
nite of copper and has the following composition : Cop- 
per oxid, 31.29 per cent., arsenious oxid, 58.65 per cent., 
acetic acid, 10.06 per cent. Some of the commercial 
grades of Paris green contain soluble forms of arsenic, 
while others are adulterated with lime and insoluble sili- 
cates. The arsenic should be insoluble and have 
no injurious effect upon vegetation. In case soluble 
arsenic is present, the foliage is destroyed. Pure Paris 
green should completely dissolve in hydrochloric acid. 
In case silica is present, an insoluble residue appears 
when the material is treated with hydrochloric acid. 
London purple and various arsenates and arsenites are 
occasionally used for insecticides. London purple con- 



COPPER, ZINC, LEAD, ETC. 



153 



tains soluble arsenic. In case of accidental poisoning 
with Paris green, hydroxid of iron is usually employed 
as an antidote. 

203. Occurrence of Hercury. — Mercury is found in 
nature mainly in the form of the sulfid, HgS, commonly 
called vermilion which, when roasted, yields S0 2 and Hg. 
Mercury is extensively used in the preparation of alloys 
and amalgams. 

204. Compounds of flercury. — L,ike copper, tin and 
many other elements, mercury forms two series of salts, 
the mercurous and mercuric compounds. Mercurous and 
mercuric oxids, Hg 2 and HgO, mercurous and mercuric 
chlorids, HgCl and HgCl 2 , and the nitrates and sulfids 
are among the more important compounds of mercury. 
Mercuric chlorid is employed as an insecticide and also 
as a germicide. It is very poisonous and is very destruc- 
tive to all forms of animal and plant life ; it is frequently 
used for the treatment of fungus diseases of plants. 

Experiment 35. — Replacement of metals. Place, in separate 
test-tubes, (1) 5 cc. of silver nitrate, (2) a piece of copper, and (3) 
5 cc. of lead nitrate. To 
the first test-tube, add a 
piece of copper foil, to the 
second a small piece of 
lead, and to the third, 
a piece of zinc. After 
a few minutes, examine 
the contents of the vari- 
ous test-tubes and observe 
the results. Copper has 
the power of replacing silver in solution, lead has the power of re- 
placing copper, and zinc has the power of replacing lead. 



NDt A PRODUCE 



*==r 



*0.J 8 PBOOuC 



u 



Fig. 61. 



U 9> 



154 AGRICULTURAL CHEMISTRY 

The more electro-positive elements replace those which are less 
electro-positive. Observe in these experiments that the copper is 
coated with silver, the lead with copper, and the zinc with lead. 
Write the following reactions which have taken place : 
(i) AgN0 3 + Cu = 

(2) Cu(N0 3 ) 2 + Pb = 

(3) Pb(N0 3 ) 2 + Zn = 

Questions, (i) Which element is the most positive ? (2) What 
elements can zinc replace ? (3) Why does copper replace silver? 
(4) Why does lead replace copper ? (5) What does this experi- 
ment show as to the relative properties of the three elements, cop- 
per, silver and lead ? 



CHAPTER XXII 
Water Content and Ash of Plants 
205. Water. — Water is present in all food materials, 
and in many cases makes up a very large portion of the 
weight of a substance. In vegetables, in milk, and in 
the juices of meat, water is present to such an extent as 
to be perceptible to the senses. Substances like flour, 
meal and starch, which appear perfectly dry, are not free 




Water-oven. 



from water, but contain from 9 to 12 per cent. This 
hydroscopic water, as it is called, is held mechanically by 
the particles of which the material is composed, and the 



156 



AGRICULTURAL CHEMISTRY 



amount thus held depends upon the extent of the pre- 
vious drying of the material and the hydroscopic condi- 
tion of the air. Inasmuch as air always contains some 




Fig. 63. Analytical balance. 

water, it necessarily follows that all substances exposed 
to the air must likewise contain some water. 

In order to remove the last traces of water from a sub- 
stance, it is dried in either a water- or a hot-air oven at a 



WATER CONTENT AND ASH OF PLANTS 1 57 

temperature of ioo° C, — the boiling- point of water. This 
converts all of the water in the material into steam, 
which is then expelled. A water-oven, shown in Fig. 
62, has double walls, the space between the walls being 
partially filled with water, which is kept boiling by means 
of a gas burner placed below the oven. The substance is 
weighed in a suitable dish and then dried in the water- 
oven until the weight is reasonably constant, the loss of 
weight being considered water. 

The determination of water in foods, although appar- 
ently simple, is a difficult and troublesome chemical pro- 
cess because many foods, when heated to ioo° C, suffer 
changes, and give off volatile Organic compounds along 
with the water ; or the organic matter may undergo a 
change in composition, as oxidation. For determining 
the absolute moisture content of foods, the chemist em- 
ploys a drying bath of different pattern from that shown, 
and the material is dried in a current of some neutral gas, 
as hydrogen, to prevent oxidation of the q 

substance. All of the dishes in which /£y'^t£?\ 
the substances are placed, during anal- £ : ';. " ~ vS:.:'^\ 
ysis, are dried and cooled in desiccators %~ '^-W 
out of contact with air, so as to remove ^#^fe? 
all traces of hydroscopic moisture. The ^^0^ 
weighings are made on analytical bal- Fig. 64. Desiccator, 
arices which are scales of extreme accuracy (see Fig. 63). 
The determination of water is one of the most difficult 
parts of the analysis of plant or animal substances. 

206. Dry flatter. — The dry matter of a material is the 
portion which is left after all the water has been re- 



158 



AGRICULTURAL CHEMISTRY 



f?=G§ 




Fig. 65. 



moved. Dry matter, as the term implies, is the dry ma- 
terial free from all traces of hydroscopic moisture, and 
the amount is determined by subtracting the per cent, of 
water from 100. For example, if flour contains 12 per cent, 
water there will be 88 per cent, of dry matter. The amount 
of dry matter in substances ranges between wide limits as 7 
per cent, and less in some fruits to 99 per cent, in sugar. 
Experiment 36. — Determination of water in potato. Carefully 
■weigh an aluminum dish (Fig. 65). Cut 
thin slices from different parts of a 
potato and reduce them to 1/8-inch 
cubes. Weigh in the dish, some of 
these pieces, forming a layer not more 
than two deep. Record the weight, 
place in the dish a small piece of paper with your initials, 
then set the dish in the water-oven 
(Fig. 62), and allow it to remain 
twenty-four hours, or until the next 
exercise. After drying, weigh again, 
and from the loss of weight calculate 
the per cent, of water in the potato. 
(Weight of potato and dish before dry- 
ing, minus weight of potato and dish 
after drying, equals weight of water 
lost. Weight of water divided by weight 
of potato taken, multiplied by 100, 
equals the per cent, of water in the 
potato. ) 

Experiment 3/. — Water in flour. 
In the same manner, determine the 
per cent, of water in flour, using about 
Fig. 66. 2 grams of flour, and noting the ex- 

act weight before and after drying. 

Experiment 38. — Water in milk. Weigh a watch-glass and place 
it on the water-bath (see Fig. 66). Measure with a pipette 3 cc. of 
milk into the watch-glass. Evaporate to dryness on the water-bath, 





WATER CONTENT AND ASH OF PLANTS 1 59 

completing the process in the water-oven. When dry, weigh, and 
from the loss of weight, calculate the per cent, of solids. Sp. gr. of 
milk, 1.032. 1 cc. H 2 = 1 gram. 1 cc. milk = 1.032 grams. If 
skim milk is used, the sp. gr. is 1.035. 

Experiment 39. — Water in clover. Weigh an aluminum dish. 
Take three or four large clover plants and cut fine with shears or 
knife. Weigh a portion in the dish ; dry, and weigh again as in 
Experiment 36. Determine the per cent, of water in clover. 

Questions. (1) How did the potato, after drying, compare in 
appearance and volume with the material before drying? (2) How 
does the percentage amount of water which you have obtained, 
compare with the figures given in the tables of analysis. (3) In 
the determination of water in milk, what was the appearance of the 
milk solids? (4) What classes of compounds are present in milk 
solids. (5) How does the amount of water obtained in Experi- 
ment 37 compare with the amount given in the tables of analysis? 
(6) What would be the shrinkage in weight of a barrel of flour if 
2 per cent, of moisture were removed, and what would be the in- 
crease in weight if 2 per cent, of moisture were absorbed from the 
air? (7) How does the amount of water obtained in Experiment 39 
compare with that obtained from the other materials? (8) How 
much water is present in a ton of green clover ? 

207. Plant Ash. — The ash of a plant, or of any ma- 
terial, is that portion which remains after the substance 
is burned at the lowest temperature necessary for com- 
plete combustion. It is sometimes spoken of as the min- 
eral or inorganic part, also as the non-volatile part, and 
includes all of the materials, with the exception of water 
and nitrogen, which the plant takes from the soil during 
growth. The term ash as used in chemistry differs from 
the term as ordinarily used in that the chemical ash is 
pure ash, free from unburned particles of carbon, and also 
contains elements, as sodium, chlorin, sulfur and phos- 
phorus, traces of which are volatile at a high tempera- 



i6o 



AGRICULTURAL CHEMISTRY 



ture. Crude ash is obtained by burning a substance 

until all of the carbon is 
oxidized. 

Experiment 40. — Determina- 
tion of ash. Weigh to the 
second decimal place in grams, 
a dish given out for this experi- 
ment. Then weigh into the dish 
about 2 grams of dry clover or 
other hay, place in the muffle 
furnace, and let it remain until 
there is no charred material left. 
Cool on an asbestos mat. Weigh 
again and determine the per 
cent, of ash from the material 
taken and the weight of the ash 
obtained. Calculate the per 
cent, of organic matter. Save 
the ash for future experiments. 
[The 500, 200, and 100 mg. 
weights are to be recorded as 
0.5, 0.2, and o. 1 gram ; the 50, 




Fig. 67. — Muffle furnace used for 
determination of ash. 



20, and 10 mg. weights as 
0.05, 0.02, and 0.01 gram. 
If one used a 10-gram 
weight, a 500-mg. weight, 
and a 20-mg. weight, it 
would be written 10.52 
grams.] 

208. Form of the 
Ash Elements. — 

None of the elements 
present in the ash of 
plants ever exist there 




Fig. 68.— Weights for balance. 



WATER CONTENT AND ASH OF PLANTS l6l 

in the elementary or free state, as free sodium or free 
silicon, but they are always in chemical combination, 
forming salts, or are combined with the elements 
which constitute the organic part of the plant. The 
ash elements are never present in the form of free acids or 
free bases, although, in chemical analyses, they are ex- 
pressed as acid or basic oxides. Phosphorus, for exam- 
ple, never exists in the plant as free phosphorus or as 
phosphoric acid, but either as a phosphate or combined 
with some of the elements which constitute the organic 
part. 

209. Amount of Ash in Plants. — While the amount 
of ash in plants is fairly constant, it will be found to vary 
with the stage of growth, climatic conditions, and na- 
ture of the soil. In mature agricultural plants, the amount 
rarely exceeds 10 per cent, of the dry weight of the ma- 
terial. Clover grown in different localities is found to 
contain from 6 to 8.5 per cent, ash ; other crops also 
show limited variations. The ash is not evenly dis- 
tributed throughout all parts of a plant ; the leaves, for 
example, contain a larger amount than the seed. In the 
case of corn, the amount of ash in different parts is as 
follows : 

Per cent. 

Mature plant 5.8 

Roots 3.5 

Leaves 8.1 

Stems entire 6.6 

Grain 1.4 

As previously stated, the ash elements of a plant, to- 
gether with the nitrogen and water, represent all of the 



1 62 AGRICULTURAL CHEMISTRY 

material which is taken from the soil. In ioo parts of 
the dty material of any crop, from 5 to 10 parts are 
derived from the soil while 90 to 95 parts are supplied 
either directly or indirectly from atmospheric sources. 

210. Importance of Ash Elements. — Plant ash is com- 
posed of potassium, sodium, calcium, magnesium, iron, 
phosphorus, sulfur, silicon, and chlorin compounds. 
These elements, with a few others present in small 
amounts, as aluminum and occasionally manganese, boron, 
etc. , are the elements which make up the mineral matter 
of plants. Some of the ash elements, as potassium and 
phosphorus, are absolutely necessary for the life of the 
plant, while others, as aluminum and silicon, are, so far 
as known, unnecessary. The essential ash elements are 
potassium, calcium, magnesium, iron, phosphorus and 
sulfur. The non-essential elements are sodium, silicon, 
chlorin, and aluminum. But in some alkali and sea 
plants, sodium, chlorin, and other elements are essential 
for growth. 

Chemically considered, the elements found in the ash 
of plants are divided into two classes : 

(1) Metals or base-forming (2) Non-metals or acid-forming 

elements. elements. 

Potassium K Phosphorus P 

Sodium Na Sulfur S 

Calcium Ca Silicon Si 

Magnesium Mg Chlorin CI 

Iron Fe 

Aluminum Al 

To the above list must be added small amounts of 
other elements occasionally found in the ash of plants, 



WATER CONTENT AND ASH OF PLANTS 



163 



and also oxygen, which is in chemical combination with 
all of the above elements. 

The essential ash elements are absolutely necessary 
for the normal growth and development of plants. They 
take a direct part in the production of plant tissue. The 
part which each ash element takes in plant growth 
has been known only for a comparatively short time. At 
one time, it was believed that the ash elements were 
largely accidental that the plants in taking up water from 
the soil could not well keep out the soluble earthy mat- 
ters, but the methods of sand and water culture have 
demonstrated the necessity and the functions of the 
various ash elements. 

an. Water Culture. — In water-culture experiments, 
the seed is germinated and then the roots 
are suspended in water containing small 
amounts of the different ash elements. The 
roots are protected from the light, and the 
solution is frequently changed. In case it 
is desired to learn what effect the absence 
of an element has upon the growth and de- 
velopment of the plant, all of the elements 
are supplied in known amounts except the 
one in question which is withheld alto- 
gether. The development of the plant is 
observed, and if it reaches maturity and 
produces fertile seeds, it is concluded that 
the element withheld is not necessary to plant 
growth, while on the other hand, if the plant does not de- 
velop naturally, the element withheld is considered a nee- 




Fig. 69.— Water 
culture. 



164 AGRICULTURAL CHEMISTRY 

essary one. By eliminating the ash elements in order, a 
conclusion may be drawn as to the part which each separate 
element takes in plant nutrition. After repeated experi- 
ments with various modifications, aided by chemical and 
microscopic examinations of the plant, the functions of an 
element are determined. When a plant develops under 
normal conditions, there is a definite part which every es- 
sential element performs during growth. In fact, a plant 
may be fed, and the effects of the food be observed 
as accurately as in the case of the feeding of men or 
animals. 

212. Sand Culture is essentially the same in principle 
as water culture. Pure sand (Si0 2 ) is treated with strong 
acids, washed with distilled water, and ignited. When 
properly prepared, this leaves a perfectly sterile medium 
to which is added, as desired, known amounts of the 
various ash elements. 

Occurrence and Function of Ash Elements 

213. Potassium. — Potassium is one of the most im- 
portant and least variable of all the elements found in 
the ash of plants. It is quite evenly distributed through- 
out the growing plant and generally occurs in the entire 
plant in the largest proportion of any of the essential ash 
elements. It is taken up in the early stages of plant 
growth and is always present to the greatest extent in the 
active and growing parts, as in the leaves where the pro- 
duction of plant tissue occurs. Potassium is one of the 
elements most essential for the plant's development. 

The function of potassium is apparently to aid in the 



WATER CONTENT AND ASH OF PLANTS 



165 



production and transportation of the carbohydrate com- 
pounds, as starch and sugar, and thus indi r ectly in the 
formation of all organic matter. In sugar- 
and starch-producing crops, as sugar-beets 
and potatoes, it takes an important part in 
the growth and development. Potassium 
doubtless has much to do in the way of 
regulating the acidity of the sap by forming 
organic salts such as potassium bitartrate in 
grapes. At the time of seed formation 
there is a slight retrograde movement 
of the potash, in some cases a small 
part being returned to the soil. The 
supply of available potash in the soil has 
great influence upon the vigor of plant 
growth. Weak and sickly plants are always 
deficient in potash. Some crops require 
more for growth than do others and some 
experience difficulty in obtaining it. Some 
plants contain such large amounts of potash 
that they are called ' ' potash plants. " 

Experiment 41. — Alkalinity of ashes. Weigh 2 without potash, 
grams hard wood ashes into a beaker containing 100 cc. H 2 0. Heat 
over a sand-bath until it boils ; filter. To one-half of filtrate, add 
10 drops of cochineal solution ; from the burette (see Fig. 38), add 
dilute (1 cc. acid, 40 cc. H 2 0) HC1 until the solution is neutral. 
The alkali in wood ashes is mainly K 2 C0 3 which is neutralized 
with HC1. Write the reaction. Test both leached and unleached 
ashes. Note number of cubic centimeters HC1 used in each case. 
What do the results indicate ? 

214. Sodium. — This element, which resembles potas- 



1 66 AGRICULTURAL CHEMISTRY 

siura in its chemical deportment, is not absolutely neces- 
sary for agricultural plants and does not occur in the ash 
in such large amounts as potassium. Nearly all agricul- 
tural plants are brought to maturity without its aid 
except for the small amount in the seed. The amount, 
if any, which plants require is very small, not sufficient 
to take into consideration. It is supposed to be present 
as an accidental ingredient, because sodium chlorid is 
universally present in the soil, in water, and occasionally 
traces of it are in the air ; hence plants could not very 
well exclude it. Some alkali plants require and store up 
large amounts of sodium compounds. Unlike potassium, 
sodium is not so evenly distributed through the plant. 
It has no special movement, but is found mostly in the 
lower parts of the plant. Seeds contain but little of it, 
more being present in the straw and stems. 

215. Calcium. — This element is always present in the 
ash of plants. None of the higher plants can reach 
maturity without a normal supply. Some, like clover, 
beans, peas, and lucern, require so much for their develop- 
ment that they are called ' ' lime plants. ' ' Accumula- 
tions of lime are found in many leafy plants, particularly 
clover, where crystals of calcium oxalate may be 
observed. In leaves, it appears to have the special func- 
tion of aiding in the construction of the cell walls. 
No new plant cells can be produced without the aid of 
calcium. 

From the culture experiments of various investigators, 
the element calcium appears to take a prominent part in 
the production of new tissues. Whenever it is withheld, 



WATER CONTENT AND ASH OF PLANTS I 67 

the growth of the plant is restricted. Some plants, after 
their growth has been checked by withholding calcium, 
will show increased vigor within a few hours after 
it is supplied. Calcium is assimilated in the early- 
stages of plant development. In wheat, for example, 
80 per cent, is assimilated before the plant heads 
out. Calcium assists in imparting hardiness to crops. 
It does not accumulate in the seeds to such a great extent 
as do other elements. Only about a tenth of the total 
amount removed in grain crops is in the seeds, the re- 
maining nine-tenths being present in the straw. Crops 
grown on lime soils are usually well nourished, and are 
more capable of withstanding unfavorable climatic condi- 
tions as drought and early frosts than are crops not so 
liberally supplied with lime. 

Experiment 42. — Lime, CaO, in plant ash. Transfer the ash 
from Experiment 40 to a beaker containing 5 cc. HC1 and 50 cc. 
H 2 Q ; heat ten minutes, filter, and divide into two portions. Save 
portion for Experiment 44. Make one portion neutral with am- 
monia, NH,OH. Add 5 cc. NH 4 C1 solution. To the solution, 
add 5 cc. ammonium oxalate, f NH^C^ ; note the precipitate 
which is calcium oxalate, CaC 2 4 . 

Into a separate test-tube put 0.1 gram CaCl,, add 5 cc. H 2 and 
a little HC1 until acid ; then nearly neutralize with NH,OH and 
add NH4CI and (NH 4 ) 2 C 2 4 . Compare this precipitate with that 
from the clover ash. Observe, in this second test, that you 
have taken a pure calcium salt, and that the same precipitate was 
given as by the plant ash. Write the following reactions which 
have taken place : CaC-A + Heat =? CaC0 3 + HC1 =? CaCl 2 + 
(NH 4 ) 2 C 2 4 =? 

216. Magnesium is also an essential element. It occurs 
in all plants and farm crops in somewhat smaller amounts 



1 68 AGRICULTURAL CHEMISTRY 

than calcium but in the seeds of grains it is stored up 
three times more liberally. Magnesium is assimilated 
more slowly than calcium ; in fact it is assimilated, as a 
rule, more slowly than any other ash element. The 
plant does not require magnesium until the approach of 
seed formation, although a small amount is necessary for 
perfect leaf action as it enters into the chemical compo- 
sition of the chlorophyl. When plants are grown with an 
incomplete supply of magnesium, the seeds are frequently 
sterile. In culture experiments, the absence of magne- 
sium is not observed so much in the first stages of growth 
as when the time of seed formation approaches when its 
absence is followed by restricted development. 

217. Aluminum is found in the ash of many plants, as 
wheat, peas, beans, and rice, although it occurs in very 
small amounts and, so far as known, is not essential for 
plant growth. Most soils contain traces of soluble sili- 
cates of aluminum, and hence plants cannot well be free 
from it. 

218. Iron in small amounts is necessary for plant growth. 
It occurs in about the smallest amount of any of the ash 
elements, but is always present in plants. When plants 
are unable to obtain their requisite supply of iron, the 
production of chlorophyl does not take place and they 
fail to develop a normal green color. 

The function of the iron is to assist in the formation of 
chlorophyl, the coloring-matter of plants. It is not known 
whether iron enters into the chemical composition of the 
chlorophyl, or is simply organically associated with it 



WATER CONTENT AND ASH OF PLANTS 



169 



219. Phosphorus, in the form of phosphates, is found 
in all parts of plants. It is one of the essential elements 
for plant growth. Its function is to aid in the produc- 
tion and transportation of the proteid bodies. The phos- 
phorus and nitrogen compounds are closely associated in 
the work of producing proteids which can take place only 
in the plant cells. The proteid compounds produced in 
the leaves of plants are finally transported to the seed. 
Many proteids which are insoluble in water are soluble 
in the presence of phosphate compounds. The phos- 
phates are essential ,in the early stages 
of the plant's development. In the case 
of wheat, 80 per cent, is assimilated in 
the first fifty days, and in other crops, 
the assimilation is equally rapid. The 
phosphates accumulate to a greater extent 
in the seeds of grains than in the leaves 
and stems. From 60 to 75 per cent, of 
the total phosphates is removed in the 
seeds. The loss of phosphates from the 
farm is one of the reasons why soils de- 
cline in fertility. 

Experiment 43. — Phosphoric acid in seeds. 

Crush 25 kernels of wheat in a mortar. Place 

the crushed wheat in a small Hessian crucible 

and ignite; when cool, transfer the charred 

mass to a small beaker. Add 10 cc. HN0 3 and 

50 cc. H.,0, and boil ten minutes. Break up the 
, , ' . , ... ... , , . Fig. 71. -Plants grown 

charred particles with a stirring rod during with and without 

the boiling. If the beaker shows signs of be- P hos P horic acid - 

Filter. 




coming dry, add a little hot water. 



To half the filtrate, 



170 AGRICULTURAL CHEMISTRY 

add 3 cc. ammonium molybdate. The yellow precipitate is am- 
monium phosphomolybdate. See Experiments 17 and 18. 

220. Sulfur also is an essential element of plant and 
animal bodies, but occurs in plant tissue in comparatively 
small amounts. It enters into the composition of albu- 
min and other proteids. Sulfur is used by plants only 
in the form of sulfates. The part which it takes in plant 
life is to supply the sulfur for the proteid compounds 
which always contain this element in chemical combi- 
nation. Culture experiments have shown that in its 
absence no growth results. 

Experiment 44. — Sulfur as sulfates in plant ash. To the second 
portion of the filtrate from Experiment 40 add 2 cc. barium chlorid 
(BaCl 2 ), observe the result, and write the reaction, assuming SO s 
to be in the form of K 2 S0 4 . In a second test-tube, add a few 
crystals of Na 2 S0 4 or K 2 S0 4 to 10 cc. H 2 containing a few drops 
HC1. When dissolved add BaCl 2 and compare with precipitate 
obtained in first part of experiment (see Experiment 21). 

221. Chlorin is not an essential ash element. It accu- 
mulates mainly in the lower part of the plant, and its pres- 
ence appears to be accidental, it having no decided func- 
tions to perform. The statements made about sodium, 
its occurrence, distribution, and importance apply also 
to chlorin with which it is combined forming sodium 
chlorid. 

222. Silicon occurs in all plants. It is found in largest 
amounts in the dense and older parts, as in the stalk and 
straw, where there is less activity. In some of the lower 
plants, as diatoms, there is so much silica that when the 
organic matter is removed by burning, a skeleton of silica 



WATER CONTENT AND ASH OF PLANTS 171 

is left. It was formerly supposed that silica gave the 
stems of grains and grasses their stiffness. Perfect wheat, 
however, with normal strength of straw has been grown 
in the absence of silica, except for the small amount 
originally present in the seed. Lawes and Gilbert have 
shown that the lack of silica is not the cause of grain 
lodging. Some authorities claim that silica takes a part 
in plant economy and is necessary in seed formation. 
Whatever its function, it is not an important element as 
plant food, and there is always an abundance in the soil 
for crop purposes. 

In the living plant, the mineral elements are not pres- 
ent in the same form or combination as in the plant ash. 
During growth, many of the ash elements are combined 
with the organic compounds, for example phosphorus, 
which forms phosphorized proteids and fats. The ash forms 
a part of the plant tissue. When the plant is burned, the 
organic compounds are volatilized, while the ash elements, 
which are non-volatile, are left. The essential ash ele- 
ments are absolutely necessary, as food, for the growth 
and development of all crops, and plant growth is fre- 
quently arrested because of the lack of a sufficient supply 
for purposes of nutrition. The food requirements of in- 
dividual farm crops are discussed in the " Chemistry of 
Soils and Fertilizers." 



172 



AGRICULTURAL CHEMISTRY 



Summary Table. 
Plant ash elements. 



Occurrence. 



Function. 



Potassium K 9 



Sodium 



Calcium 



Na 2 
CaO 



Magnesium MgO 

Iron Fe 2 3 

Aluminum A1 2 3 

Manganese Mn 2 3 

Non-metals. 
Phosphorus P 2 O s 



Sulfur 



Silicon 
Chlorin 



SO, 

SiO, 



+ 



+ 



+ 



Mainly in the ac- 
tive growing parts 
of plant leaves and 
stems. 

Stems and roots. 

Leaves and stems. 

Seeds and leaves. 
Leaves and stems. 



Lower parts 
plants. 

Lower parts 
plants. 



of 
of 



+ Seeds. 



+ 



Assists in formation 
of starch, carbohy- 
drates and in plant 
growth in general, 
and makes plants 
vigorous. 

No function. 

Assists in formation 
of plant cells, and 
makes plants hardy. 

Aids in seed forma- 
tion. 

Aids in chlorophyl 
formation. 

No function. 
No function. 



Leaf action and for- 
mation and move- 
ment of proteids. 

Production of pro- 
teids. 

No apparent function 

No apparent function 



- Stems and leaves. 

- Lower parts. 

Problem 1. — How many pounds of potash are removed from an 
acre of soil yielding 150 bushels of potatoes? 

The potatoes weigh 60 pounds per bushel. 150 X 60 = 9,000 
pounds, total yield of potatoes. The potatoes contain 24 per cent, 
dry matter (see Table). This dry matter contains 3.8 per cent, 
ash. Hence 2,160 pounds dry matter contain (216 X 0.038 = 81.9) 
81.9 pounds ash. 60 per cent, of this ash is potash ; or (81.9 X 
0.60) 49.1 pounds are potash. Therefore, 150 bushels of potatoes 



WATER CONTENT AND ASH OF PLANTS 




air dry, approximately 87 
per cent. 



approximately 90 P 
per cent. g 



173 



COW W 

o o o 



** H O 

o o o 



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vO <X W WW h COCn (04^ OOwO mOOWHMWhO!^ 



Os » 

On h OS 
O O *■ 



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SO Os^> CO Os Os O O O 4^ to to 4^ to WsO O (MJ WWW m O 

P HI H H M M W ; W O^OO OOMl-.p>-l"w0^ 1 

CO -1 w mm os^J -P' • OS 00 CO 0061 4^ CO^l M-<i'io m 1-1 Os 'i. 

M^.O WOi-iOO'^J Cn W W ^1 OsW O 1-1 Os4* vO CO O £> 

W 1H M M HI M WWW4^4^4^Wt04*- > _, 

to to ps Ji4i-|iMM m o\ s£> Cn m O COCn ~-J to Oi vi Oi tn ^J ," 

^j to co to cn bovb h h io h bo co bs bosb sb -t^. bs-<r h bssb P 

woos 4^ sO hi O O s£> 4^ Jiji O U> OSOWOOM^O-I^to? 

; 4^. ps ^ c*> ; ; 1 ; ! ! '. J* J ww 10 j p h h h ; „ 

• to 61 bo to • • be • 4^> i- i» • ~j to bo-<» • o 

•OO OO O • Oi-iO-COCOOsO'^ 

Cn J> Os 4^ W 10 W 

H to to 1-1 Os^J CnCnCnOs O 4s* to Os O H H O M HCn^O O {D 

00K) h Q~~lCnCnJ>Cn^vI — W ^ « OssO W COHW\b lO^J O 

OCOO OOOOOOO CO^t s) CO Ui m O MOM O OW »" 

cnj>w w j> ; ; ; ; ; ; ! V 1 i I -1 . M . M ! ° ° '-' ° ! n 

b bo 4^ to j> • • io • bo bs to • sb 4^- b sb • — 

OOO OO • • O • O O W • m CO to 4=» " ' 



B n 
p <-* 

ll 

: |3* O 

5- 
• ? - 
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■ p 
i-t 



174 AGRICULTURAL CHEMISTRY 

remove from the soil 49. 1 pounds of potash. In the same way, the 
amount of each separate element removed from the soil can be 
calculated. 

Problem 2. — Calculate the pounds of total ash, K 2 0, CaO, MgO, 
and P 2 5 removed in 25 bushels of wheat. 

Problem 3. — Calculate the same ingredients removed in 1,500 
pounds of wheat straw. Compare these amounts with the corre- 
sponding elements removed in the grain (Problem 2). 

Problem 4. — Calculate the CaO, MgO, K 2 0, and P 2 5 removed 
in 50 bushels of oats weighing 32 pounds per bushel. 

Problem 5. — Calculate the same for 40 bushels of barley weigh- 
ing 48 pounds per bushel. In what respects does the mineral food 
of barley differ from the mineral food of wheat? 

Problem 6. — How much P 2 5 is removed in 15 bushels of flax ? 



CHAPTER XXIII 
The Non-Nitrogenous Organic Compounds of Plants 

223. Organic flatter. — The organic matter of a plant 
or material of any kind is that portion which can be 
converted into volatile or gaseous products ; it is 
the combustible part, and is simply a mechanical mix- 
ture of the various organic compounds, as starch, sugar, 
and fat, of which the material is composed. The term 
organic compounds was originally applied to those bodies 
which it was believed could be produced only as the re- 
sult of life processes, but it is no longer used in that sense 
because many of the organic compounds are now produced 
in the laboratory by synthetic methods independent of 
life processes. The organic matter of a substance is ob- 
tained by subtracting the ash from the dry matter. The 
dry matter of wheat, for example, contains 2.10 per cent, 
ash and 97.90 per cent, organic matter. The organic 
matter of plant and animal bodies includes a number of 
classes and types of compounds. 

224. Non-Nitrogenous and Nitrogenous Organic Com- 
pounds. — For purposes of study, the organic compounds 
of animal and plant bodies are divided into two large 
classes : (1) nitrogenous, and (2) non-nitrogenous. This 
division is made on the presence or absence of the element 
nitrogen. The nitrogenous or nitrogen-containing com- 
pounds are those in which the element nitrogen is in 
combination with carbon, hydrogen, oxygen, and small 
amounts of other elements, while the non-nitrogenous 



176 



AGRICULTURAL CHEMISTRY 



compounds are those which contain no nitrogen but are 
composed of carbon, hydrogen, and oxygen. Starch, 
sugar, and fat are types of non-nitrogenous compounds, 
while albumin, casein, and fibrin are types of the nitroge- 
nous. 

225. Classification of Non~Nitrogenous Compounds. — 
There are six large divisions of the non-nitrogenous com- 
pounds : (1) carbohydrates, (2) pectose substances, (3) 
fats, (4) organic acids, (5) volatile or essential oils, and 
(6) mixed compounds. Each division is, in turn, di- 
vided into various subdivisions and groups : 

(i. Carbohydrates, 
Cellulose, 
Starch, 
Sugar, 
Pentosans, 
Gums. 
Pectose substances (jellies). 

!i. Olein, 
2. Stearin, 
3. Palmitin, etc. 

fi. Tartaric, 
2. Oxalic, 
3. Malic, etc. 
Volatile or essential oils. 
Mixed compounds. 

Carbohydrates 

226. General Characteristics. — The carbohydrates are 
the first subdivision of the non-nitrogenous compounds, 
and include the starches, sugars, gums, and cellulose and 
pentosan bodies. They form the largest group of or- 
ganic compounds in plants, and in many plants and food 



Organic non-nitrogenous 
compounds. 



ORGANIC COMPOUNDS OF PLANTS 1 77 

materials, are present largely as starch. The carbohy- 
drates occur in plants in three physical forms : ( 1 ) As 
the framework of the plant cells, as cellulose, (2) in 
solution in the plant sap, as sugar, and (3) deposited as 
solid substances within the plant cells like starch. In 
coarse fodders, as hay, they are largely in the form of 
cellulose and pentosan bodies. While the various carbo- 
hydrates differ chemically and physically, they all possess 
a few common characteristics : ( 1 ) they are all neutral 
bodies, and (2) they all contain twice as many hydrogen 
as oxygen atoms in their molecules. The H and O are 
present in the same proportion as found in water, viz. , 
2 atoms of H and 1 of O. In starch, C 6 H 10 O 5 , the H and 
O would form 5H 2 0. 

Cellulose 

227. Occurrence.— Cellulose is found most abundantly 
in the stems, roots and leaves of plants, particularly at ma- 
turity. Cellulose is the structural 
basis of the vegetable world, and 
forms the framework of every 
plant cell. In some plants it is 
the most abundant material pres- 
ent ; in hay and coarse fodders 
it makes up from 30 to 40 per 

, r , 1 j . , ^ Fig. 72.— Cell structure of 

cent. 01 the dry matter. Crops plant tissue. 

like cotton, flax and hemp contain large amounts, and 

are cultivated mainly for the cellulose which they yield. 

228. Physical Properties. — Pure cellulose is a colorless, 
insoluble material, differing in texture according to its 




i 7 8 



AGRICULTURAL CHEMISTRY 




source. In hemp, it is flexible and tenacious, while in 
wood, it is hard and compact, in 
the pith of the elder, it is elastic, 
in the potato, porous, and in ger- 
minating seeds, loose and spongy. 
Cotton and filter-paper are ex- 
l amples of nearly pure cellulose. 
The proportion and properties 
of cellulose in a food influence 
its digestibility. Some foods are 
less valuable because of the 
tenacious character of the cellu- 
Fig. 73.— Flax fiber. lose, which prevents the cells 

from undergoing disintegration and digestion. 

229. Chemical Properties. — Cellulose is composed of 
carbon, hydrogen and oxygen. Its formula is C 6 H 10 O 5 . 
Cellulose from one source may contain a different multiple 
of C 6 H 10 O 5 than that from another source. In young and 
growing plants, the cellulose is in a hydrated condition ; 
that is, water is chemically united with the cellulose 
molecule, as (C 6 H 10 O 5 .H 2 O) n . Hydrated cellulose is more 
readily acted upon by chemicals than are other forms. 
As the plant develops, the cellulose is gradually dehy- 
drated and this is one reason why cellulose, at different 
stages of growth, has a different food value. Ligno- 
cellulose is found in wood and many mature plants. It 
contains a larger per cent, of carbon than cellulose. 

230. Function and Value. — In the plant, the function 
of cellulose is to form the structural part of the cell walls. 
It constitutes the main part of the walls of every plant cell. 



ORGANIC COMPOUNDS OF PLANTS 1 79 

In seeds, it is a reserve material, finally used as food by 
the young plant. Commercially, cellulose is used for 
making paper, cloth, guncotton and other explosives, and 
is extensively used in the arts. 

231. Food Value. — The food value of cellulose depends 
upon its degree of hydration. Hydrated cellulose, when 
digested, has practically the same food value as starch. 
Lignocellulose is indigestible, and has no food value. 
Indirectly, a minimum amount of cellulose imparts a 
mechanical value to a food by acting as an absorbent for 
concentrated waste products. When crops are cut and 
cured while some of the cellulose is in a hydrated condi- 
tion and but little has passed into the ligno form, the 
cellulose is valuable as food. 

232. Amount of Cellulose in Plants. — Cellulose is 
found more abundantly in the stems and leaves of plants 
than in the seeds. In the straw of wheat, oats, rye, and 
barley, it makes up from 35 to 45 per cent, of the dry 
material. It also constitutes a large portion of the roots 
of plants. In seeds, the amount of cellulose is small, and 
usually ranges from 2 to 5 per cent., while in wood, the 
amount is large, and ranges from 50 to 80 per cent. In 
tables of analyses, the cellulose is usually included with 
other bodies under the head of crude fiber. 

233. Crude Fiber. — Crude fiber includes the cellulose, 
lignin and other bodies which make up the framework of 
vegetable substances. In vegetable foods, as flour and 
the cereal products, the amount of crude fiber is small 
compared with that in many other plant bodies. Crude 



l8o AGRICULTURAL CHEMISTRY 

fiber and cellulose are not identical terms. In the chem- 
ical analysis of plants, the crude fiber is determined by- 
first digesting the material in dilute sulfuric acid to 
dissolve all soluble bodies as sugar, hydrolyzed starch, 
some of the proteids and related bodies. The substance 
is then digested with dilute sodium hydroxid to remove 
all compounds which have failed to dissolve in the acid. 
Crude fiber and insoluble mineral matter are about the 
only substances which are insoluble in the dilute acid and 
alkali, hence the fiber is obtained by dissolving all other 
compounds and deducting the insoluble mineral matter 
left. For the determination of cellulose more exact 
methods have been devised. The crude fiber determina- 
tion, however, is valuable because it shows the amount 
of fibrous material contained in plants. 

Experiment 43. — Preparation of cellulose. Place in a beaker 
about 1 gram of ground straw or hay ; add 200 cc. of water, and 
20 drops of H 2 S0 4 . Boil on the sand-bath twenty minutes, and 
after the material settles, pour off the liquid, then add 100 cc. water, 
and wash thoroughly by decantation. Add 200 cc. water and 4 cc. 
NaOH solution, boil twenty minutes, and wash the fibrous material 
as before. Place some of the crude fiber in a test-tube, add 5 cc. 
HC1, 10 cc. H 2 0, and a crystal of KC10 3 ; heat, and then wash the 
cellulose product. 

Questions. ( 1 ) What element was liberated by the action of 
HC1 upon the KCIO3 ? (2) What effect did this element have in the 
bleaching and purification of the crude fiber? (3) In what other 
experiment has this element been used as a bleaching reagent? 

(4) When examined with a lens, how did the cellulose appear ? 

(5) Is cellulose soluble in dilute acids? (6) Why were the dilute 
acid and alkali solutions used in this experiment? (7) What be- 
comes of the ash or mineral matter in the material used in this ex- 



ORGANIC COMPOUNDS OF PLANTS l8l 

periment? (8) What does this experiment show in regard to the 
properties of cellulose ? 

Starch 

234. Occurrence. — Starch is found most abundantly in 
the seeds, roots, and tubers of plants, being stored up in 
those parts which are concerned with new growth. 
During growth, starch is produced in the leaves of all 
green plants ; at maturity, it is stored in the seed or tuber. 
It is present in the plant cells as granules which have 
regular organized forms. 

235. Physical Properties. — The starch granules from 
a given cereal are always constant in form and physical 
properties. Each grain is composed of overlapping layers 
which can be observed under the microscope. The walls 
of the layers are composed of a material called ' ' starch 
cellulose ' ' ; between the walls is the pure starch known 
as granulose. All starch grains have a somewhat similar 
general structure. Starch is insoluble in cold water, be- 
cause the walls of starch cellulose prevent the water from 
dissolving the pure starch. In hot water some of the 
granulose is dissolved and a paste is formed. Pure dry 
starch is tasteless and odorless. Starch is exceedingly 
hydroscopic, and commercial starch always contains from 
10 to 12 per cent., or more, of water. A food which 
contains a large amount of starch will vary in moisture 
content and weight according to the hydroscopicity of the 
air. The starch grains obtained from different cereals 
and food products vary in form according to the source 
from which they are obtained. Wheat starch is circular 



182 



AGRICTJI/TTJRAI, CHEMISTRY 




in outline, and has a slightly concave center. There are 

but few markings or 
rings (see Fig. 74). 
The granules vary- 
in size from 0.05 to 
0.01 millimeter in 
diameter. Corn- 
starch is somewhat 
smaller (0.02 to 0.03 
millimeter), more 
angular than wheat 
starch, and has a 
Fig. 74.— wheat starch. star-shaped center 

or helium (see Fig. 75). Oat starch is composed of 

a number of small 

segments forming a 

compound grain, or 

mass, each segment 

in itself a complete 

structure. Barley 

and rye starch 

grains are somewhat 

similar to wheat. 

In some vegetables, 

as the parsnip, the 

starch grains are 

minute. Fig. 75.— Cornstarch. 

236. Chemical Properties. — Starch is composed of car- 
bon, 44.44 per cent. ; hydrogen, 6.17 per cent. ; and 
oxygen, 49.39 per cent. Its formula is (C 6 H 10 O 5 ) n . The 




ORGANIC COMPOUNDS OF PLANTS 1 83 

value of n has been variously estimated from 2 to 200. 
The different starch grains, as of wheat, corn and oats, 
are all composed of the same elements, C, H, and O, and 
differ in form because these elements are put together in 
a different way in each. When acted upon by heat, as in 
the popping of corn, the starch grains are ruptured. At a 
temperature above 120 C, starch is changed to dextrin. 
In the presence of water and dilute acids, starch gradually 
undergoes hydration ; that is, water is chemically added 
to the molecule. By the joint action of heat, ferments, 
and various chemicals, starch is converted into a number 
of products, as soluble starch and dextrose. In the 
presence of iodin, starch is colored blue, different kinds 
of starch giving different shades and tints. The nature 
and mechanical form of the starch granules in a food, 
determine, to a slight extent, its rapidity and ease of di- 
gestion. Some starches are more easily digested than 
others, and all undergo important chemical and physical 
changes in the cooking and preparation of food. Since 
starch makes up such a large portion of many human and 
animal foods, its composition, properties, and food value 
are of prime importance. 

237. Function and Value. — In the seed, starch is a 
reserve form of food for the use of the young plant before 
it is able to obtain its own food ; in roots and tubers also, 
it is stored up for that purpose. Many crops, as pota- 
toes, corn, and sago, contain so much starch that they 
are often cultivated for starch-making purposes. Starch 
is obtained mechanically from potatoes by first pulping 
to break the cells, and then washing the pulped mass 



184 AGRICULTURAL CHEMISTRY 

with water from which the starch slowly settles. In the 
arts, starch is used in many ways. As a food, it is used 
mainly in its original form associated with the other or- 
ganic compounds with which it is found in plants. 

238. Food Value of Starch.— Starch is a valuable, nu- 
trient, and when digested produces heat and energy. 
When burned in the bomb calorimeter 1 pound of 
digestible starch produces i860 calories. A calorie 
is the unit employed for measuring heat, and is 
the amount of heat required to raise 1 kilo of water i° C, 
or approximately 1 pound of water 4 F. One gram 
of starch yields 4.2 calories. Pure starch alone is inca- 
pable of sustaining life because it contains no combined 
nitrogen, and does not supply any material for repairing 
the tissues of the body or for the construction of new 
nitrogenous tissue. When associated with nitrogenous 
compounds, starch can be used by the body for the pro- 
duction of fat as well as for the production of heat 
and energy. 

239. Amount of Starch in Plants. — In grains, the 
amount of pure starch ranges from 50 to 75 per cent, of 
the dry weight of the material ; in hay and forage crops, 
it is small, usually less than 2 per cent. The amount of 
pure starch in some of the cereals and farm crops is ap- 
proximately as follows : 

Pure starch. 
Per cent. 

Wheat 68 

Wheat flour 72 

Oats 55 

Corn 75 



ORGANIC COMPOUNDS OF PLANTS 1 85 

Pure starch. 
Per cent. 

Rice 78 

Potatoes 80 

Wheat bran 8 

Straw less than 1 

Hay - 1 to 3 

Experiment 46. — Preparation of potato starch. Reduce one or 
two clean potatoes to pulp on the grater. Tie the pulp in a clean 
cloth and squeeze into a large cylinder filled with water, occa- 
sionally dipping the bag into the water. Allow the cylinder to 




Fig. 76. — Obtaining starch from potato, 
stand for twenty minutes, or until the starch has all settled ; pour 
off the water. If the starch is not clean, wash by adding more 
water, and allow it to settle again ; then pour off the water. 
Leave the cylinder in the desk until the starch is dry. Save this 
starch for the following tests : 

Tests for starch. Place 0.5 gram of starch in a test-tube about 
one-half full of water. Shake the test-tube, boil, and filter ; then 
to this filtrate add a few drops of iodin. 

Questions. (1) What was the difference in the action of hot an 



1 86 AGRICULTURAL CHEMISTRY 

cold water upon starch ? (2) How did this difference show itself 
in the tests? (3) Why in the one test-tube were there a blue mass 
and a clear liquid, and in the other opposite results ? 

240. Dextrin is a carbohydrate which has the same 
general formula as starch from which it differs in struc- 
tural composition. Dextrin is produced from starch by 
the action of heat. At a temperature of 163 C. moist 
starch is changed to dextrin. When this change takes 
place, nothing is added to or taken from the starch mole- 
cule. The three elements, C, H and O, are simply rear- 
ranged in a different way in the new molecule. Dextrin 
is not found naturally in food products to any apprecia- 
ble extent, but is present in starch-containing foods which 
have been subjected to the action of heat. The brown 
crust of bread is composed mainly of dextrin. Dextrin 
is soluble in water, and is more readily digested than 
starch, but has the same general fuel and energy-produ- 
cing value. 

Experiment 47. — Preparation of dextrin. Place about 2 grams 
of flour in a porcelain dish ; heat cautiously on a sand-bath for five 
minutes constantly stirring, so that it will not burn. When cool, 
add three times its bulk of water and heat nearly to boiling ; ob- 
serve the appearance of the solution ; then filter. The filtrate con- 
tains dextrin. To a portion, add twice its bulk of alcohol; the 
dextrin is precipitated. To another portion, add a few drops of 
iodin solution ; blue color indicates soluble but unaltered starch. 

Questiotis. (1) What agent was employed to change the starch 
to dextrin? (2) How does dextrin differ from starch in solubility? 
(3) Is dextrin soluble in alcohol ? (4) In what ways does dextrin 
differ from starch ? 

241. Structural Formulas. -Cellulose, starch, dextrin 
and inulin have the same general formula (C 6 H 10 O 5 j n , but 



ORGANIC COMPOUNDS OF PLANTS 1 87 

all differ in both physical and chemical properties. This 
is because the elements, C, H and O, are put together in 
different ways in the three compounds. For example, a 
pile of bricks may be put together to form one structure, 
and then again in different ways to form other structures; 
in each structure there are the same number and kinds 
of bricks. So in the molecules of starch, dextrin, inulin 
and cellulose, there are the same number and kinds of 
atoms, but in each they are combined in a different way. 
In the study of the composition of plants, organic com- 
pounds are frequently met with which have the same 
general composition, but different chemical and physical 
properties. Whenever two compounds have the same 
general formula and percentage composition, but differ- 
ent chemical and physical properties, the difference is 
said to be one of structural composition. 

Sugar 

242. Classification of Sugars. — As commonly used, 
the term sugar is applied to the product obtained from 
sugar-cane or sugar-beets. As used in chemistry, it in- 
cludes a large class of compounds of which maple-, cane-, 
and beet- sugar are examples of only one division. The 
two main classes of sugars present in plant bodies are 
sucrose and dextrose; occasionally, other sugars are found. 

The sucrose group includes cane-, beet-, maple-, milk-, 
and malt-sugar. These sugars have the general formula 
C 12 H 22 O n , and are characterized by the molecule contain- 
ing 12 atoms of carbon. The dextrose group includes 
glucose, levulose, galactose, and all sugars having the 
general formula C 6 H 12 6 . This group is characterized by 



1 88 AGRICULTURAL CHEMISTRY 

the molecule containing 6 atoms of carbon. The term 
monosaccharide is applied to the dextrose group, and 
disaccharide to the sucrose group. 

243. Occurrence of Sucrose. — Sucrose is found in plants 
in largest amounts of any of the sugars. Juices from the 
sugar-cane and sugar-beet contain from 12 to 18 per cent. 
It is also present in small amounts in seeds and cereal 
products. From 1.5 to 2 per cent, is found in sweet corn 
and about 0.50 per cent, in wheat flour. In some fruits, 
as apples, sucrose is present to the extent of 5 per cent, 
or more. 

244. Physical and Chemical Properties of Sucrose. — 

The chemical and physical properties of sucrose obtained 
from the sugar-cane or sugar-beet are alike in all respects. 
When the two sugars have been subjected to the same 
degree of refining, they are identical. When examined 
under the microscope, sucrose is in the form of regular 
crystals, as shown in the illustration (see Fig. 
77). At 160 C. sucrose crystals melt, and 
when cool form a colorless, glassy mass. A 
„. _ concentrated solution boils at a little above 

FJg- 77-— Su- 
crose crystal. ioo o q ^ 160 C. a brown product known 

as barley sugar is formed. At 200 C. sucrose is decom- 
posed, and gases, as carbon monoxid, carbon dioxid and 
methane, are given off. In concentrated solutions, a tem- 
perature of ioo° C. causes an inversion ; that is, the su- 
crose molecule is split up and two new sugars are formed, 
namely : dextrose and levulose. Hence, in the refining 
of sugar, the concentration must be carried on in vacuum 




ORGANIC COMPOUNDS OF PLANTS 1 89 

pans. In the presence of all acids, even dilute organic 
acids, hydrolysis or inversion of sucrose takes place. 

245. Milk-Sugar (lactose) is found in cow's milk to 
the extent of 4.5 to 5 per cent., and is present in the 
milk of all mammals. It has the same general but a dif- 
ferent structural composition from sucrose. 

246. rialtose is a sugar produced in the malting of 
barley and other grains by the action of ferments upon 
starch, the reaction being 

2C,H„0 6 = H 2 + C 12 H 22 O n . 
Maltose is not found to any extent in plant bodies, but is 
present in prepared foods which have undergone the malt- 
ing process. 

247. Inversion of Sucrose. — When sucrose is acted 
upon by heat and dilute acids, as well as other chemicals, 
inversion takes place. One molecule of water is chemi- 
cally united to one molecule of sucrose which splits up 
and forms the two sugars, levulose and dextrose. 

Sucrose. Levulose. Dextrose. 

C 12 H 22 O n + H 2 = C 6 H 12 6 -f- C 6 H 12 6 . 
This process takes place in the ripening of fruits and in 
the curing of many fodders, as well as in the cooking and 
preparation of human foods. 

Experiment 48. — Inversion of cane-sugar. Place 2 grams 
sugar, 30 cc. H 2 0, and 2 cc. H 2 S0 4 in an evaporator. Heat 
fifteen minutes on a sand-bath, replacing the water lost by 
evaporation. Neutralize with CaC0 3 and filter, adding more 
water if necessary for filtration. Test 5 cc. of the filtrate with 
an alkaline solution of copper sulfate (Fehling's solution) 
as directed in Experiment 34. Take 0.1 gram of sugar, dis- 



190 AGRICULTURAL CHEMISTRY 

solve in 10 cc. cold water, add 2 cc. alkaline copper sulfate solution, 
and heat cautiously for about a minute. Cane-sugar, unless in- 
verted, gives no reaction with copper sulfate solution. Compare 
this result with the first test. Observe that in the first test the same 
precipitate is obtained as in Experiment 34. 

Qiiestions. (1) What is meant by inversion of cane-sugar? (2) 
Why was hot sulfuric acid used ? Write the reaction. (3) Why 
was CaC0 3 used? (4) What becomes of the calcium salt when the 
solution is filtered? (5) What was the result when the filtrate was 
heated with alkaline copper sulfate solution (Fehling's solution)? 
(6) Did the sucrose, when tested, give any reaction with this 
reagent? (7) Under what condition in nature does this process of 
inversion take place ? (8) What are invert sugars ? 

248. Refining of Sugar. — At the present time, the 
larger portion of commercial sugar is obtained from sugar- 
beets. In the diffusion process of manufacture, the beets, 
after cleaning and slicing, are passed into large tanks, 
where they are subjected to water under pressure which 
removes the sugar by liquid diffusion. The impurities 
associated with the sucrose are precipitated with lime 
water, Ca(OH) 2) the excess of lime being removed by 
carbon dioxid gas which converts the calcium r^droxid 
into insoluble calcium carbonate. For the purpose of pro- 
ducing the pure lime and the carbon dioxid gas, lime- 
stone is burned in specially constructed kilns at the sugar 
factory. After the removal of the impurities and 
lime, the solution containing the sugar is concentrated in 
a large vacuum pan and allowed to crystallize ; the crys- 
tals are then washed in centrifugal washing machines 
and granulated. Commercial sugar is ordinarily about 
99 per cent, pure sucrose. 

249. Occurrence of Dextrose. — Dextrose occurs widely 



ORGANIC COMPOUNDS OP PLANTS 191 

distributed in nature. It is found in small amounts in 
the sap of saccharine plants, in seeds, ripe fruit, honey, 
animal tissues, and all food products in which the 
sucrose has undergone inversion. 

250. Chemical and Physical Properties. — Dextrose is a 
solid, white substance which gives off water from its mole- 
cule when heated to 170 C. At 200 C, volatile gases 
and acid products are formed. Acids and alkalies act 
upon dextrose and produce a large number of compounds. 
Dextrose is capable of undergoing a number of different 
kinds of fermentation, alcohol, succinic acid, lactic acid, 
and glycerol being some of the products formed. When- 
ever foods which contain dextrose are exposed to favor- 
able conditions, fermentation takes place. Dextrose is 
produced commercially by the action of dilute acids upon 
starch. The acid causes a molecule of water to unite 
chemically with a molecule of starch. 

C 6 H 10 O 5 + H 2 O = C 6 H 12 O 6 . 

The thick syrup that is formed after the acid is neu- 
tralized is called glucose syrup. If a solid mass is pro- 
duced, it is called grape-sugar. 

Experiment 49. — Preparation of glucose. Add 20 drops H 2 S0 4 
to about 70 cc. water iu an evaporator. Heat on the sand-bath 
until the boiling-point is reached. Then add 2 grams of pulver- 
ized starch. Observe the appearance of the starch immediately 
after adding. Heat twenty-five minutes, stirring occasionally, and 
replacing the water should too much evaporate. Add CaC0 3 to 
neutralize the H 2 S0 4 ; when neutral to test paper, filter, washing 
the contents of the filter with 25 cc. of water. Take a few drops of 
the filtrate and test with iodin for starch. Then evaporate the rest 
of the filtrate to about 20 cc. and observe its appearance. 



192 AGRICULTURAL CHEMISTRY 

Tests for glucose. Place about 3 cc. of glucose solution in a test- 
tube, add 3 cc. alkaline solution of copper sulfate, called Fehling's 
solution (see Experiment 34), and heat. Then take about 0.1 gram 
of glucose from the shelf bottle, dissolve it in 5 cc. water, add 3 cc. 
Fehling's solution. Heat, and compare with the first test. 

Questions. ( 1 ) Why was sulfuric acid used in this experiment ? 
(2) What chemical change did the starch undergo? Write the 
reaction. (3) Why was CaC0 3 used? Write the reaction. (4) 
Was any reaction obtained with iodin for starch? (5) What was 
the result when the glucose solution was added to the hot alkaline 
solution of copper sulfate ? (6) How did this precipitate compare 
with that obtained when glucose from the shelf bottle was used ? 

251. Levulose, commonly called fruit-sugar, is formed 
along with dextrose whenever sucrose undergoes inver- 
sion. It has the same formula as dextrose, C 6 H 12 6 , but 
different chemical and physical properties, due to a differ- 
ent structural composition. Levulose is very sweet, and 
is found in many ripe fruits and vegetables. Its proper- 
ties are somewhat similar to those of dextrose, but it is 
more susceptible to the action of heat, acids, and alkalies, 
and less to the action of ferments. 

Experiment 50. — Levulose and reducing sugars from carrots. 
Reduce a small clean carrot to a pulp. Place the pulp in a beaker 
and add 200 cc. water. After half an hour, filter, heat the filtrate 
for fifteen minutes and then filter a second time. Evaporate 50 cc. 
of the filtrate nearly to dryness. Test a portion with Fehling's 
solution as in Experiment 49. 

Questions. ( 1 ) How was sugar separated from the carrots ? 
(2) What was the result when the filtrate was heated, and what 
compounds were precipitated ? (3) Describe the appearance of the 
concentrated filtrate. (4) What reaction was obtained with 
Fehling's solution? (5) How does levulose differ in composition 
and properties from dextrose ? 



ORGANIC COMPOUNDS OF PLANTS 



193 



252. niscellaneous Sugars. — A number of sugars that 
do not belong to either the dextrose or sucrose group 
are found in plants. Raffinose, for example, is a sugar 
found in small amounts in beets and other vegetables. 
It is capable of being converted into dextrose sugars by 
treatment with dilute acids. 

253. Optical Properties of Sugar. — Sugars are charac- 
terized as optically active or inactive. Those which 
have the power of turning a ray of polarized light to the 
right are called dextrorotatory while those which turn the 
ray to the left are called levorotatory. Polarized light 
has no action upon the inactive sugars. This principle 
is taken advantage of in the commercial testing of sugar 
by means of the polariscope which is a piece of apparatus 
so constructed that the number of degrees which a ray of 




Fig. 78. — Polariscope. 

polarized light is diverted in passing through a solution 
of sugar can be accurately measured, and the purity of 



194 AGRICULTURAL CHEMISTRY 

the sugar determined. A given weight of pure sucrose 
dissolved in a definite amount of water always turns a ray 
of polarized light a definite number of degrees which are 
accurately measured by the polariscope. Any decrease 
in purity influences proportionally the angle of diver- 
gence of the polarized light. Hence, if the angle of 
divergence of a commercial sugar is determined, its purity 
is likewise determined. 

254. Sugar-Beets are usually paid for on the basis 
of their content of sugar and the purity of the juice. 
For sugar-making purposes, the higher the content of 
sugar and the purer the juice, the more valuable the 
beets. Ordinarily, sugar-beets contain from 12 to 16 per 
cent, sugar ; occasionally as low as 8 and as high as 20 
per cent. In addition to sugar, the beet juice contains 
other solids, as small amounts of organic acids, albumin 
and pectin . When the content of solid matter is 20 per 
cent, and 16 of the 20 parts are sugar, the juice has a 
purity coefficient of 80 ( 16 / 20 X 100). 

255. Food Value of Sugar. — When properly combined 
and used with other foods, sugar is a valuable nutrient 
for the production of heat and energy. L,ike starch, it 
is incapable of sustaining life unless associated with nitroge- 
nous compounds. One pound of sugar, when burned, 
yields 1.5 pounds of carbon dioxid and 0.58 pound of 
water. 

C 12 H 22 O n + 24O = i2C0 2 + H 2 0. 
In a ration, sugar is considered as having the same 
caloric value as starch, viz., 1 pound yields i860 
calories. 



ORGANIC COMPOUNDS OF PLANTS 1 95 

T56. Gums. — Closely related to the sugars are the 
gums, like gum arabic, and those which exude from 
peach and cherry trees. In the seeds of many grains, 
there are also gum-like bodies. When treated with di- 
lute acids, the gums are converted into dextrose sugars 
and acid products. Bassorin, or mucilage, as flaxseed 
mucilage, is found in a few seeds and fruits. The for- 
mula for some of the gums is the same as for sucrose sugars 
and dextrose. 

257. Pentosans. — The pentosans are a class of carbo- 
hydrates present in liberal amounts in many plants. They 
are insoluble, and aid the cellulose in giving form and 
structure to plant tissues. When acted upon by dilute 
acids, the pentosans are rendered soluble, while true cel- 
lulose is insoluble. They are called pentosans because 
they yield a sugar which contains five atoms of carbon 
in the molecule. When acted upon by the digestive 
fluids they are rendered soluble and available as nutrients. 
In some fodders they form a large part of the nitrogen- 
free extract. The digestible pentosans are considered as 
having the same food value as other digestible carbohy- 
drates. The amount of pentosans in some common foods 
is approximately as follows : 

Per cent. 

Hay, timothy 20 

Linseed meal 12 to 15 

Wheat bran 1 7 to 22 

Wheat 4 to 6 

Oats 12 

Corn 5 

Barley 5 to 7 

Flour trace 

258. Peptin Bodies are present in many ripe fruits and 



196 AGRICULTURAL CHEMISTRY 

vegetables. They are jelly-like substances, which are 
soluble in hot water, and are commonly known as fruit 
jellies. When treated with dilute acids, digestive fluids, 
and other reagents, the pectin bodies are converted into 
dextrose sugars and other products. Potatoes, turnips, 
beets, and all fruits contain pectin. In unripe fruits, and 
in some uncooked vegetables, the pectin is in the form of 
acid bodies which are insoluble and indigestible. In the 
last stages of ripening, the pectin of fruits and vegetables 
undergoes a change to soluble forms. Soluble pectin is 
considered to have the same food value as the soluble 
carbohydrates. 

Experiment 5/. — Pectose from potatoes. Reduce a small clean 
potato to a pulp. Squeeze the pulp through a clean cloth into a 
beaker, add 10 cc. H 2 0, and heat on a sand-bath to coagulate the 
albumin. Filter, add a little hot water if necessary. To the filtrate 
add a little alcohol. The precipitate is the pectose material. 

Questions. ( 1 ) Is the pectose from the potato soluble ? ( 2 ) 
Is pectose coagulated by heat? (3) Is it soluble in alcohol? (4) 
In what ways does pectose differ from sugar? (5) In what ways 
does it resemble sugar ? 

259. Nitrogen=Free Extract. — In the processes of chem- 
ical analysis of plants and foods, the chemist determines the 
water, ash, crude protein, ether extract, and crude fiber, 
and classes the remainder in one group or division called 
nitrogen-free extract. Wheat, for example, contains : 

Per cent. 

Water 9.25 

Ash 2.95 

Crude protein • • • • 13.25 

Ether extract 2.20 

Crude fiber 2. 25 

Total 29.90 

100 — 29.90 = 70.10 per cent, nitrogen-free extract. 



ORGANIC COMPOUNDS OF PLANTS 197 

The term nitrogen-free extract means that the bodies 
contain no nitrogen ; they are nitrogen-free or non-nitroge- 
nous, and are soluble in dilute acids and alkalies. The 
nitrogen-free extract of wheat is composed mainly of 
starch ; in some foods, as carrots, it is largely sugar. In 
human foods, the nitrogen-free extract is composed 
mainly of carbohydrates as starch and sugar, while in 
animal foods, it consists of pentoses and a large number 
of compounds dissimilar in character and food value. In 
plant bodies, the nitrogen-free extract usually constitutes 
the largest of any of the groups of compounds. Meats 
and animal products, except milk, contain only very 
small amounts. 

Fats 

260. Presence in Plants.— Fats and oils form one of 
the subdivisions of the non-nitrogenous compounds of 
plants. Fat is present in nearly all plants, but in smaller 
amounts than the carbohydrates. The fat in plants is 
produced from starch. For example, in flax, there is 
more starch than fat when the plant is growing, but in 
the mature plant, there is more fat than starch, due to the 
starch being converted into fat. This change of starch 
to fat can take place only in the plant cells ; fat, as yet, 
cannot be made synthetically. During the process of 
germination, the fat of seeds is changed back to starch. 
While fat is present in nearly all parts of plants, it is 
found most abundantly in the seeds, as of flax, rape and 
cotton, which are often called oil seeds. Fat occurs in 
the form of minute oil globules within the plant cell, and 
is removed mechanically by the aid of heat and pressure, 



198 AGRICULTURAL CHEMISTRY 

as in the manufacture of linseed, rape, cottonseed and 
other oils. It is also extracted by means of solvents as 
benzine and carbon disulfid. In roots and stems, fat is 
found only in traces. In leaves, it is often present in the 
form of a waxy coating, while in nuts it is frequently 
stored up in large amounts in the kernel. 

261. Physical Properties. — Fats are all characterized 
physically by being insoluble and of a lower specific 
gravity than water. There are a great many separate 
fats, and each has its own specific giavity and melting- 
point. As commonly found, tbey are not simple bodies, 
but mechanical mixtures of various separate fats, as 
stearin, palmitin, and olein. The fats are all soluble in 
ether, chloroform and turpentine, and differ in physical 
properties according to the proportion and kind of fats 
present. When examined under the microscope, some 
have optical properties and definite crystalline forms. 

262. Chemical Composition. — Fats are all characterized 
by having a high per cent, of carbon and a low per cent, 
of oxygen. For example, in stearin C g7 H no O & , there are 
in the molecule 57 atoms of carbon, and 6 atoms of 
oxygen. In starch and carbohydrates in general, the per 
cent, of oxygen is greater, and of carbon, less than in 
fats. 

Ultimate Composition of Fats. 

Stearin. Palmitin. Olein. Starch. 

Per cent. Per cent. Per cent. Per cent. 

Carbon. 77.6 75,9 77.4 44.44 

Hydrogen 12.4 12.2 11. 8 6.17 

Oxygen ........ 10.0 11. 9 10.8 . 49-39 



ORGANIC COMPOUNDS OF PLANTS 1 99 

Fats are organic salts, the basic part consisting of the 
glycerol radical C 3 H 5 which is combined with a fatty acid. 
Glycerin is the basic constituent common to all fats. 
One fat, as stearin, differs from another, as olein, by 
containing a different fatty acid in combination with the 
glycerol radical. When the simple fats are separated into 
their component parts, the acids formed are : stearic, 
palmitic, oleic and butyric. 

Some of the fatty acids, as stearic and palmitic, are 
solids, while others, as butyric, are volatile. Those fatty 
acids which distil with boiling water are called volatile 
fatty acids. Butter, for example, contains nearly 5 per 
cent, of volatile fatty acids, present mainly in the form of 
butyric acid. Some of the fats undergo fermentation and 
become rancid, as butterin in butter, while others slowly 
take up oxygen from the air and undergo oxidation. 
The chemical and physical properties of the fats in plants 
and foods are determined by the kinds and amounts of 
the separate fats present. Olein, stearin and palmitin 
are always present in larger amounts than are other fats. 

263. Stearin (C 57 H 110 O 6 ) is a solid fat with a high melt- 
ing-point, 69. 4 C. Beef and mutton tallow and animal 
fats in general are composed mainly of stearin. When 
pure, it is a white and tasteless body, and has a defi- 
nite crystalline structure. Stearin predominates in all 
hard fats. 

264. Palmitin (C 51 H 98 6 ) is a white, solid fat obtained 
from butter, palm oil and human fat. When chemically 
pure, it is tasteless, and crystallizes in the form of tufts 
and needles. It has a melting-point of 63 ° C. Its 



200 AGRICULTURAL CHEMISTRY 

general properties are somewhat similar to those of 
stearin. 

265. Olein (C 57 H 104 O 6 ) at moderate temperatures is a 
liquid. It solidifies at 4 C. Olein predominates in the 
oil of fish, as sperm oil and cod-liver oil. It is also present 
to a great extent in many vegetable oils, as olive oil. 
Whenever olein predominates, the fat is a liquid. 

266. Miscellaneous Fats,— In addition to the three 
fats mentioned, there are others, as butyrin, the charac- 
teristic fat of butter, and linolein, the characteristic fat of 
flaxseed. 

267. Saponification is a chemical change brought about 
by the action of an alkali, as potash or soda, upon a fat„ 
An exchange takes place between the glycerol of the fat 
and the metal of the alkali. Glycerine is a base, but 
potash is a stronger base ; hence the potash replaces the 
glycerol and forms salts, as potassium stearate or palmitate, 
according to the fat used. 

Experiment 52. — Saponification. Weigh about 20 grams of lard 
into an evaporator. Melt the lard, but do not heat above 50 C. 
Dissolve 10 grams NaOH in about 40 cc. water in a beaker. (Do< 
not let the NaOH come in contact with the scale pan.) Add this 
solution to the evaporator, stirring constantly, and leave the evapo- 
rator on the warm sand-bath, with a low flame underneath, for 
40 to 50 minutes. Then place on the sand-bath in the desk until the 
following day when a good soap should have formed. Dissolve a 
little of the soap thus produced in a test-tube with 20 cc. water. 
Divide the solution into two parts ; to one add a little salt, and to- 
the other a few drops of HC1. 

Questions. ( 1 ) Why was NaOH used in this experiment, and 
what portion of the fat did it replace ? (2} What other material & 



ORGANIC COMPOUNDS OF PLANTS 201 

could be used in place of NaOH? (3) What influence did the salt 
have upon the soap solution? (4) What was the result when 
HC1 was added to the soap solution? (5) Why is it neces- 
sary to weigh both the lard and the NaOH ? (6) What would be 
the result if the fat and alkali were taken in different proportions 
from those used in this experiment? (7) Why does soap form an 
insoluble mass with hard waters ? 

268. Fatty Acids. — Formic acid, found in pine needles 
and in red ants, has the formula H 2 C0 2 which is also 
written HC0 2 H. Acetic acid has the formula H.CH 2 . 
C0 2 H, and differs from formic acid simply in containing 
CH 2 more than found in formic acid. If CH 2 were added 
to acetic acid, H.C 2 H r CO — H, propionic acid would be 
produced. This is present in some plants. In like 
manner, butyric acid can be produced from propionic 
acid. By the addition of CH 2 , about twenty acids can be 
formed in the way described. This list includes palmitic, 
stearic and other acids found in fatty bodies and named 
fatty acids ; various of these are present in nearly all 
foods. When a series of compounds, like the fatty acids, 
shows a uniform difference between two adjacent members 
the term homologous series is employed. 

269. Waxes. — Wax is similar in composition to fat, 
but contains an ethyl radical in place of the glycerol 
radical. Beeswax, for example, is composed of palmitic 
acid and ethyl radicals. Waxes, like fats, undergo saponi- 
fication and are considered as having the same food 
value. 

270. Food Value of Fat.— Fat is the most concentrated 
non-nitrogenous nutrient of foods. On account of con- 



202 AGRICULTURAL CHEMISTRY 

taining such a large amount of carbon and small amount 
of oxjrgen, fat, when either burned or oxidized as food, 
produces 2.25 times more heat than the same weight of 
starch or sugar. One gram of fat yields 9.2 calories, and 
1 pound, 4225 calories. The fact that so much more 
heat is produced from the oxidation of fat is apparent 
when the products of oxidation of starch and fat are 
compared. 

Stearin. 
C 5 tH 110 O 6 + 163 O = 5 7C0 2 + 55H 2 

890 2508 990 

1 pound of fat produces 2.8 pounds 
C0 2 + 1.1 pounds of water. 

Starch. 

C 6 H 10 O 5 + 120 = 6C0 2 + 5 H 2 

162 264 90 

1 pound of starch produces t.6 
pounds C0 2 + 0.56 pound H 2 0. 

890 parts, by weight, of fat produce, when burned, 2508 
parts, by weight, of carbon dioxid and 990 parts 
of water. 162 parts, by weight, of starch produce 
264 parts, by weight, of carbon dioxid and 90 parts of 
water. One pound of fat yields 2.8 pounds of carbon 
dioxid and 1.1 pounds of water, while one of starch yields 
1.6 of carbon dioxid and 0.56 of water. Fat produces 
approximately 2.25 times more heat than starch. 

271. Amount of Fat in Plants and Foods. — The 

amount of fat in various plant substances ranges from a 
few hundredths of a per cent, in tubers to 35 per cent, 
and more in flaxseed. Of ordinary grains, oats and corn 
are the richest in fat and contain from 3.5 to 5 per cent., 
while wheat and rye have about 2 per cent. each. In 
hay, the amount of pure fat is less than 2 per cent., and 



ORGANIC COMPOUNDS OF PLANTS 203 

in straw it is less than 1 per cent. In nearly all food 
products, the per cent, of pure fat is included with the 
ether extract. 

Experiment 53. — Fat from wheat germ. Place 2 grams wheat 
germ in a test-tube, and add gasoline until the test-tube is about 
one-third full. Cork and shake at intervals of three or four min- 
utes. Do not let the gasoline come near the gas flame. Filter into 
a clean porcelain dish, and place the dish in an open window until 
the gasoline is evaporated. Observe the residue of fat. 

Experiment 54. — Fat from yolk of egg. Repeat the preceding 
experiment, using one-fourth of the yolk of a hard boiled egg, and 
5 cc. ether instead of gasoline. 

Questions. ( t ) What was the solvent used for separating the 
fat from the wheat germ ? ( 2 ) From the yolk of the egg ? ( 3 ) 
Describe the fat obtained from the wheat germ. (4) From the 
yolk of the egg. (5) How were the solvents removed in these 
experiments? (6) Are fats volatile bodies? (7) Why do fats ob- 
tained from different sources vary in appearance and properties ? 

272. Ether Extract. — The term ether extract is applied 
to that class of compounds which is soluble in ether. In 
the case of human foods, the ether extract consists largely 
of fats and oils with variable amounts of waxes, resins, 
chlorophyl, vegetable coloring-matters and nitrogenous 
and phosphorized bodies as lecithin. The value of the 
ether extract depends entirely upon its source ; in milk, 
meats, and cereals and their products, the ether extract 
is nearly pure fat, while in many vegetables it is less 
than half fat. Methods of chemical analysis have not, 
as yet, been sufficiently perfected to allow the separation 
and determination of the pure fat of all materials. The 
ether extract is obtained by placing a small weighed 
amount of the dry material in a tube, 3, (Fig. 79) which 



204 



AGRICULTURAL CHEMISTRY 



is then placed in a glass extractor connected with a small 
weighed flask containing ether. The flask is immersed 
in a water-bath heated by a gas 
burner, the ether is volatilized, 
and the vapor passes through 
openings 2 and 4 into the con- 
denser where it is cooled and 
falls back in drops from point 4 
on the substance at 5. The 
ether percolates through the sub- 
stance and returns to the flask. 
The fats and ether-soluble mat- 
ters are not volatilized but remain 
in the flask while the ether is 
vaporized and condensed again 
and again. After the extraction 
is completed, the ether is distilled 
from the flask, the ether extract 
dried and weighed, and the per- 
centage amount calculated. While 
the process appears to be simple, 
it is a difficult operation to con- 
trol, because even after many 
days' extraction, some materials 
will continue to give up ether 
extract, and unless unusual care 
Fig. 79— Ether extractor. is taken some of the fats are 
oxidized. Then, too, the ether extract is liable to be 
contaminated with impurities if ether of a high degree 
of purity is not used. When the determinations are made 




ORGANIC COMPOUNDS OF PLANTS 205 

under uniform conditions, the results are comparable and 
are of value when properly interpreted. 

Organic Acids 
273. Occurrence in Plants. — In all plants and vege- 
table foods, there are present bodies known as organic 
acids. An organic acid, like all acids, contains hydrogen 
which can be replaced by a metal (see Section 75). The 
negative radical of the acid contains carbon, hydrogen, 
and oxygen. For example, in tartaric acid, H 2 C 1 H 4 6 , 
the H 2 can be replaced by a metal ; C 4 H 4 6 is the tartaric 
acid radical. Organic acids, like mineral acids, are 
neutralized by bases. 

Tartaric Potassium 

acid. tartrate. 

2KOH + H 2 C 4 H 4 6 = K 2 C 4 H 4 6 + 2H 2 0. 

As a rule, the organic acids are not present in a free 
state, but are combined with base-forming elements, as 
potassium and calcium, forming organic and acid salts. 
In plants, the organic acids are found mainly in solution, 
as in the sap. When the plant matures, they are used 
either for the construction of other organic compounds, 
or are neutralized by bases to form insoluble salts, as 
calcium oxalate, and deposited as crystals in the leaves. 
A small amount of acid is found in all mature seeds, and 
during germination, some of the carbohydrates are con- 
verted into acids. In green vegetables and small fruits, 
the organic acids are found more liberally than in the 
seeds of grains ; in the leaves and stems of matured 
plants, but little acid is found. Some of the organic 
acids from fruits are of commercial value, as crude tar- 



206 AGRICULTURAL CHEMISTRY 

taric acid or argol found in grapes, and from which cream 
of tartar is prepared. There are a large number of or- 
ganic acids found in plants and food materials, and in the 
study of organic chemistry; these acids constitute an im- 
portant part. In this work, only a few of the more 
common organic acids are considered. 

274. Tartaric Acid is the characteristic acid of grapes. 
It is also found in small amounts in pineapples, cucum- 
bers and potatoes. It can be produced in the laboratory 
by the oxidation of milk-sugar and other carbohydrates. 
Crude tartar or argol, from which commercial cream of 
tartar is made, is deposited when grape juice ferments. 
When tartaric acid is neutralized with bases, tartrates 
are formed. Sodium potassium tartrate (Rochelle salt) 
is one of the most important salts of tartaric acid. 

275. Malic Acid occurs in many vegetables and small 
fruits, as tomatoes, currants and strawberries. It is the 
organic acid which occurs most abundantly in small 
fruits. Malic acid can be produced from tartaric acid 
by the action of hydrochloric acid. 

276. Succinic Acid is found in many plants., and also 
in animal tissues. Small amounts of this acid are formed 
when dextrose undergoes alcoholic fermentation. Suc- 
cinic acid occurs also in soils, particularly those of a 
peaty character. It can be produced from malic acid by 
the action of hydrochloric acid. Chemically, the three 
acids, tartaric, malic and succinic, are closely related. 

277. Oxalic Acid is found in small amounts in nearly 
all plants, particularly those of the oxalis variety. In 



ORGANIC COMPOUNDS OF PLANTS 207 

some plants, it is present in sufficient amounts to be 
poisonous. Oxalic acid can be produced, in the labo- 
ratory, by the action of nitric acid upon sugar and other 
carbohydrates. 

278. Nitric Acid is present in lemons and many small 
fruits. It is found in small amounts in peas, beans, 
vetches, and lupines, and with malic acid in cherries, 
strawberries and currants. 

Experimeni 55. — Citric acid from lemons. Measure out with 
the pipette 10 cc. of the prepared lemon juice solution. Dilute 
with about 25 cc. distilled water, and add 5 to 7 drops phenolphthal- 
ein indicator. Then add standard KOH from the burette until a 
faint pink tinge remains permanent. One cc. KOH will neutralize 
0.004 gram citric acid. How much citric acid is present ? The 
lemon juice solution is prepared by diluting the clear lemon juice 
with ten times its bulk of distilled water and filtering. 

Questions (1) Why was KOH used in this experiment? (2) 

What chemical change took place when KOH was added to the 

diluted lemon juice? (31 What change in color was observed? 

4 What was the final product formed in this experiment? (5) 

How does this experiment compare in principle with Experiment 10? 

279. Tannic Acid. — In many seeds and leaves of 
plants, bitter astringent compounds, as tannin and tannic 
acid, are found. The}- may lessen the value of a food 
because they retard the natural process of digestion. 
Tannic acid is not present in food plants in any appre- 
ciable amounts. Commercially, the tannins are valuable 
for the tanning of leather and for other purposes. Tannin- 
yielding plants are occasionally grown as marketable 
crops. 

280. Function and Food Value of the Organic Acids. 



208 AGRICULTURAL CHEMISTRY 

—The organic acids of plants are valuable mainly because 
they impart palatability to foods and exert a favorable 
influence upon digestion by stimulating the secretion and 
flow of the digestive fluids. Many of the organic acids 
have medicinal properties, and some, as oxalic acid, are 
poisonous. The organic acids cannot be considered as 
heat- or flesh- producing nutrients, but simply as food 
adjuncts. In plants, they take an important part in the 
assimilation of the mineral elements of plant food, and 
the production of new tissue. The acid sap comes in 
contact with the soil particles, dissolving the plant food 
which is then absorbed by osmosis. 

Essential Oils 

281. General Properties.— The essential or volatile 
oils are the compounds which impart characteristic taste 
and odor to plants. They differ from the fixed oils or 
fats by completely volatilizing when heated, and leaving 
no permanent residue on cloth or paper. They also have 
an entirely different chemical composition from the fats. 

282. Occurrence. — Volatile or essential soils are found, 
in some form, in nearly all plants, particularly during 
growth. In some fruits, and seeds, they impart the 
characteristic flavor and give individuality to the mate- 
rial. Oil of lemon, oil of cedar, and oil of nutmeg are ex- 
amples of essential oils. In nearly every plant, one or 
more of the essential oils is present at some period of 
growth. 

283. Chemical Composition and Properties. — The 

essential oils are mixed bodies, many of them belonging 



'ORGANIC COlvTPOTJNTDS OP PLANTS 209 

to the aromatic series of compounds (see Section 138). 
According to chemical composition, they may be divided 
into four groups, and each group in turn into a number 
of subdivisions. 

Groups. Uxamples. 

i. Terpenes, C 10 B- i6 . . . . . • Oil of lemon, oil of turpentine. 

2. Cedrenes, C 15 H 24 Oil of cedar, oil of cubeb. 

3. Aromatic aldehydes- .. Oil of cinnamon, oil of almond. 

4. Etherical salts •■- . . Pineapple and fruit flavors. 

The essential oils are separated from plants by distil- 
lation. At ordinary temperatures, most of them are 
liquids, insoluble in water, but soluble in alcohol. When 
the terpenes and cedrenes oxidize, they produce resinous 
deposits from which turpentine is obtained (see Section 
135). The aromatic aldehydes form a homologous series 
beginning with benzoic aldehyde, C 6 H 5 .CHO, and are 
present in many plants and fruits, imparting flavor. 
Ethyl formate, C 2 H 5 .HC0 2 ., peach flavor, ethyl butyrate, 
■C 2 H 5 .C 4 Hj0 2 , pineapple flavor, and amy! valerate found 
in apples, are some of the common etherical salts. 

284. Essential Oils of Agricultural Crops. — When 
hay is cut, the odor produced is due to a volatile oil . 
This material is lost when the hay is overcured or ex- 
posed to leaching rains. The characteristic odor of 
•clover, particularly pronounced in sweet clover, is due 
to an aromatic body. The odors of all fodder crops are 
imparted by characteristic essential oils. In the prepa- 
ration of hay and fodder crops, it should be the aim to 
prevent, as far as possible, any loss of essential oils. 
'This can be accomplished by cutting the fodder before it 
14 



2IO AGRICULTURAL CHEMISTRY 

is overripe, and then avoiding bleaching and leaching. 
Rape, turnips, cabbage, parsley and onions contain essen" 
tial oils. 

285. Synthetic Production of Essential Oils. — 

Nearly all of the essential oils found in fruits, as pine- 
apple flavor, peach flavor, and vanilla, are capable of 
being produced synthetically in the laboratory. They 
are definite chemical compounds, and it is only necessary 
to bring together, under the right conditions, the radicals 
or component parts for them to unite and form these 
compounds. Pineapple flavor is ethyl butyrate. The 
acid constituent of this salt, butyric acid, is found in stale 
butter, while the basic part of the radical is present in 
ether and alcohol. The chemical union of butyric 
acid and the ethyl radical gives ethyl butyrate or pineapple 
flavor. In fact, nearly all of the commercial fruit flavors 
are laboratory products. When properly made, they are 
identical with the same flavors as found in fruits, but 
frequently they contain traces of acid or alkaline products 
used in their preparation. 

286. Amount of Essential Oils in Plants. — The 

amount of essential oils in plants and foods is small, less 
than 1 per cent, and usually only a fraction of a per cent. 
This small amount is, however, sufficient to give a char- 
acteristic taste. 

287. Food Value. — Some of the essential oils of fod- 
ders, like the organic acids, exert a favorable influence 
upon digestion by imparting palatability and stimulating 
the secretion and flow of the digestive fluids. They are 



ORGANIC COMPOUNDS OF PLANTS 



211 



not heat- or muscle-forming nutrients, but simply food 
adjuncts. Some of the essential oils have medicinal 
properties, while others, as oil of bitter almonds, are 
poisonous. 

Experiment 56. — Essential oil from tea. Place 0.5 gram tea into 




Fig. 80. — Preparation of essential oils, 
a small flask, and add 50 cc. water. Connect the flask with a 
delivery tube, one end of which leads into a test-tube containing 



212 AGRICULTURAL CHEMISTRY 

water. Arrange apparatus as shown in Fig. 80. Apply heat and 
distil 3 to 5 cc. Observe odor of distillate which is the volatile oil 
of tea. Repeat this experiment, using sweet or red clover. 

288. Miscellaneous Compounds of Plants. — Not all 

of the non-nitrogenous compounds present in plants are 
included in the subdivisions : carbohydrates, fats, organic 
acids and essential oils. The most important and more 
common ones are, however, included in the above list. 
There are a great many others which, for convenience of 
classification, are called miscellaneous or mixed com- 
pounds. 

289. Relationship of Non-Nitrogenous Compounds 
of Plants. — A marked general relationship exists between 
many of the non-nitrogenous compounds. For example, 
the various carbohydrates are capable of undergoing 
chemical changes in which one form is changed to 
another. Starch can be converted into cellulose, sucrose, 
maltose or any other carbohydrate, and conversely cellu- 
lose can be converted into starch or other similar com- 
pounds. These changes take place during plant growth, 
particularly in the germination of the seed, and are 
brought about by the action of ferment bodies which 
cause either the addition or elimination of water from the 

molecule, as 

2 C 6 H 10 O 5 + H 2 O = C 12 H 22 O n . 

Not all of these reactions can take place in the laboratory. 
Starch may be changed to glucose or maltose, and sucrose 
may undergo inversion and form invert sugars, but 
sucrose cannot be made in the laboratory ; neither can 
starch or cellulose be made from glucose. During 



ORGANIC COMPOUNDS OF PLANTS 213 

germination, some of the carbohydrates are converted 
into organic acids. 

The fatty acids are the characteristic constituents of 
fats. In germinating seeds, fat is formed from starch by 
the addition of oxygen. The pectose substances are 
capable of being separated in the laboratory into glucose 
and acid products. Likewise the glucosides may be split 
up into glucose and acid bodies. In fact, the various non- 
nitrogenous compounds of plants, considered as a whole, 
are more or less related in chemical composition. 

290. Food Value of the Non-Nitrogenous Com= 
pounds. — As a class, the non-nitrogenous compounds 
are valuable as heat- and energy-producing nutrients. 
They do not all have the same caloric or fuel value ; for 
example, a gram of starch yields 4.2 calories, while a gram 
of fat yields 9.2. As a rule, the more concentrated the 
compound is in carbon, the greater is its fuel value. When 
properly associated and combined with the nitrogenous 
compounds, the non-nitrogenous nutrients of plants may 
produce fat in the animal body. A few of the non- 
nitrogenous compounds, as the essential oils, have but 
little direct value as nutrients. Others, as some bitter 
principles and tannic compounds, may lessen the value of 
foods or impart a negative value. The carbohydrates, 
fats, and related non-nitrogenous compounds take an im- 
portant part in the nutrition of man and animals, and 
many foods owe their value entirely to the fats and car- 
bohydrates which they contain. 



CHAPTER XXIV 
Nitrogenous Organic Compounds of Plants 

291. Amount of Nitrogenous Matter in Plants. — 

As a rule, less than 15 per cent, of the dry matter of 
plants is nitrogenous material. In the seeds of legumes, 
as beans and peas, this amounts to about 22 per cent. In 
nearly all plants, the non-nitrogenous compounds are 
from six to ten times more abundant than the nitrogenous. 

292. Different Terms Applied to Nitrogenous Com- 
pounds. — Unfortunately, the various terms used to desig- 
nate the nitrogenous compounds have not been uniformly 
applied. The terms nitrogenous compounds, proteids, 
crude protein, and albuminoids have been used synony- 
mously, but each applies to a different class of bodies. 
The terms organic nitrogenous compounds and crude 
protein are the most satisfactory when, applied to the 
entire group ; proteids and albuminoids are subdivisions 
of the nitrogenous compounds. 

293. Complexity of Composition. — The nitrogenous 
compounds are more complex in composition than the 
non-nitrogenous. The percentage composition and for- 
mulas of nearly all of the non-nitrogenous compounds of 
plants have been determined, and while the percentage 
composition and the physical and chemical properties of 
the more important nitrogenous compounds are known 
no definite formulas have, as ) r et, been applied because of 
the complexity of their molecular structure. The nitroge- 



NITROGENOUS ORGANIC COMPOUNDS OF PLANTS 215 

nous compounds are composed of carbon, hydrogen, 
nitrogen, and oxygen, and many contain in addition to 
these, phosphorus, sulphur and other elements. 

294. Classification of Nitrogenous Compounds. — 

For food purposes, the nitrogenous compounds of plant 
and animal bodies may be divided into four groups : (1) 
Proteids, (2) albuminoids, (3) amides, and (4) alka- 
loids. There are a few nitrogenous compounds in plants 
that do not find a place in any of the above subdivisions. 

Proteids 

295. General Composition.— Proteids are complex 
nitrogenous compounds that contain about 16 per cent, of 
nitrogen and less than 2 per cent, of sulfur. The per 
cent, of the different elements in protein compounds from 
various sources ranges as follows : 

Per cent. 

Carbon.- 51.2-54.7 

Hydrogen 6. 7-7.6 

Nitrogen 15. 2-18.0 

Oxygen 20. 2-23.5 

Sulfur 0.3-2.0 

It was believed, at one time, that all of the various 
compounds called proteids had, in common, a nitrogenous 
radical in their molecule to which the name protein was 
given, but this hypothesis has not been found correct. 
The term protein has been retained but without reference 
to the supposed protein radical. 

296. Occurrence. — Proteids are found more abun- 
dantly in the seeds of plants than in the leaves or other 
parts, and are always present in the active living cells of 



2*16 AGRICTUVTURAI, CHEMISTRY" 

both plants and animals. The proteids take an important 
part in life processes, protoplasm being largely of a 
proteid nature. In the growing plant,, the proteids are- 
found most abundantly in the leaves ; at maturity, they 
are stored up in the seed for the future use of the embryo;. 
The proteids occur either in a soluble form in the liquids 
of plant and animal tissues or in a semisolid, insoluble- 
condition as a part of the tissues. The proteids from; 
animal and plant sources are closely related, but are not 
in every respect identical. For food purposes, however, 
they may be jointly considered. 

297. Physical Properties, — While the members of 
the proteid group differ materially,, they alii have certain- 
physical properties in common. All are optically active 
and turn polarized light to the left. The soluble proteids,. 
with the exception of peptones and proteoses, are coagu- 
lated by heat. The proteids show a wide range in solu- 
bility, but all are soluble in either acid or alkaline solu- 
tions. As a class, they do not crystallize, and are- 
diffusible with the exception of the peptones and pro* 
teoses. 

298. Chemical Properties.— In structure the proteid 
molecule is an exceedingly complex and unstable body. It 
is readily acted upon by ferments and chemicals. Nitro- 
gen seems to form a weak link in the chain of elements. 
Proteids unite with acids and alkalies to form acid, and* 
alkali proteids. In plants, the proteids are generally united 
with small amounts of organic acids and mineral com- 
pounds, particularly phosphorus and potassium. They 
all respond to certain reactions: (1) Nitric acid gives a. 



NITROGENOUS ORGANIC COMPOUNDS OF PLANTS 2'IJ 

permanent yellow color; (2) a solution of mercury and 
nitric acid, known as Millon's reagent, gives a brick-red; 
color with the acid if heated ;. ( 3 ) a solution of copper 
sulfate and potassium hydrate gives a violet-colored solu- 
tion. The proteids, found in living cells, have different 
properties from those in dead tissue. Proteids readily 
undergo oxidation, and are chemically altered in the 
preparation of many foods. When the protein molecule 
is acted upon by heat, a large number of products are 
formed, as fatty acids, amides, aromatic bodies, ammonia, 
and carbohydrate-like bodies. The most common change 
which the proteids undergo is the rearrangement of the 
atoms and radicals in the molecule. The coagulation 
of albumin by heat is a chemical reaction in which the 
atoms and radicals in the albumin molecule are sim- 
ply rearranged structurally. The fact that it is possi- 
ble for such a large class of compounds as the proteids 
to be composed of only a few common elements, and 
for the various members to have different properties, 
is accounted for by differences instructural composi- 
tion. 

Experiment 57 . — Testing for nitrogenous organic compounds. 
Mix 0.5 gram dry clover with enough soda lime to half fill a test- 
tube. Connect the test-tube with a delivery tube, one end of 
which leads into another test-tube containing water. Apply heat 
for from five to seven minutes. Test the distillate with test paper. 
(Soda lime has the power to decompose proteid material and 
liberate the N as NH 3 . The C and O of the proteid unite and form 
C0 2 andH 2 0.) 

Questions. ( 1 ) What reaction was obtained when the distillate 
was tested with litmus ? (2) What compound was produced which 



218 AGRICULTURAL CHEMISTRY 

gave this reaction ? (3) What does this indicate that clover con. 
tains? (4) Why was this compound liberated? 

299. Classification of Proteids. — For purposes of 
study, the proteids may be divided into five classes : (1) 
Albumins, (2) globulins, (3) albuminates (casein), (4) 
peptones and proteoses, and (5) insoluble proteids. 

There are some proteids that do not belong to any of 
the above divisions. The albumin, albuminate (casein), 
and the insoluble proteids are those found most abun- 
dantly in plant and animal bodies. 

300. Albumins. — The albumins are proteids soluble 
in water and easily coagulated by heat. Egg albumin, 
serum albumin and lactalbumin, are examples of animal 
albumins. Wheat, oats, rye and nearly all vegetables, 
when extracted with water, yield some albumin which 
can be coagulated by heat or precipitation with chemicals. 
In many vegetables, the albumin is lost when the mate- 
rial is soaked in water for any length of time. Potatoes, 
for example, lose a large amount of their albumin if 
soaked in cold water before boiling. 

Experiment §8. — Tests for albumin. In each of four separate test- 
tubes, place a 3 cc. portion of a solution of egg albumin. To No. 1 
add 3 cc. strong alcohol. To No. 2, add 2 cc. HN0 3 and heat ; 
when cool, add NH 4 OH. To No. 3, apply heat. To No. 4, add a 
few drops of lead acetate. 

Questions. (1) What change occurred when the solution was 
heated? (2) When alcohol was added? (3) When HN0 3 was 
used and heat applied ? (4) What did the Pb(C 2 H 3 2 ) 2 do ? (5) 
What do these tests show in regard to the properties of albumin. 

Experiment 59. — Albumin and allied proteids from oats. Place 
in a flask 10 grams of ground oats and 50 cc. of water. Cork and 



NITROGENOUS ORGANIC COMPOUNDS OF PLANTS 219 

shake vigorously ; let stand for half an hour or until the next day. 
Filter (if not clear refilter) and make the following tests with 
separate portions of the nitrate. (1) To 5 cc. add a few drops of 
tannic acid. (2) To 5 cc. add a few drops of lead acetate. 

Questions. ( 1 ) What were the results when tannic acid and lead 
acetate were added ? (2) Do the tests indicate any large amount 
of albumin ? (3) How do these tests compare with those of the 
preceding experiment? 

301. Globulins form a group of proteids insoluble in 
water, but soluble in dilute salt solution. When animal 
or vegetable substances, as meat, eggs, wheat, rye or oats, 
are treated with dilute salt solutions (NaCl), after re- 
moval of the albumins, soluble proteid substances called 
globulins are obtained which are coagulated by heat. 
There are a large number of vegetable globulins. The 
chief globulin of meat is myosin. When meat is soaked 
in a dilute salt solution, and then cooked as food, the 
myosin is extracted and lost. In strong salt solution, 
myosin and other globulins are insoluble ; hence the use 
of strong brine in the curing of meats. In the blood, 
there are globulins present, and in the yolk of an egg, a 
globulin-like body, vitellin is found. As a rule, globulins 
do not make up a very large proportion of the proteids of 
foods. 

Experiment 60. — Obtaining globulin from oats. To the residue 
left in the flask from Experiment 59, add 2 grams of salt and 50 cc. 
water. Shake vigorously and, after one hour, filter and make the 
same tests as in Experiment 59. Save the residue in the flask for 
Experiment 65. 

Questions. ( 1 ) What results were obtained when the solution 
was tested with lead acetate and tannic acid? (2) What do these 
results indicate ? (3) What are globulins ? 



220 AGRICULTURAL CHEMISTRY 

Experiment 61. — Separation of meat globulin or myosin. Test 
as follows four 3 cc. portions of myosin solution, prepared by soaking 
fresh meat in a 5 per cent, salt solution. To the first, add a few 
drops of alum solution. To the second, add a few drops of lead 
acetate. To the third, add salt until the solution is saturated. 
To the fourth, apply heat. 

Questions. (1) What result was obtained with the alum solution 
and what does this indicate ? (2) What did the lead acetate and 
the salt solutions do? (3) What was used as the solvent for the 
myosin? (4) What is myosin? (5) What are the properties of 
myosin ? 

302. Albuminates. — The albuminates are a group of 
proteids widely distributed in both animals and plants. 
They ma}' be produced by the action of either dilute acids 
or alkalies upon albumins or globulins. The albuminates 
are insoluble in water, and when an acid albumin is 
neutralized with an alkali, the albuminate is precipitated. 
In like manner, an acid precipitates an alkali albumin. 
Casein is an albuminate present in milk, and is in a semi- 
soluble form combined with some of the mineral matter. 
Casein is soluble in dilute alkalies, but is precipitated by 
acids. In plants the albuminates are sometimes called 
vegetable casein. From peas, a casein-like body can be 
extracted. 

Experiment 62. — Separation of meat albuminate or syntonin. To 
3 cc. portions of prepared syntonin solution, add: To the first, Na 2 CO s 
until neutral, avoiding excess as it dissolves the precipitate ; to the 
second, add NaOH a drop at a time until neutral ; to the third, add 
a few drops of lead acetate. Syntonin solution is prepared by cutting 
fresh meat into small pieces, and extracting it for four hours, in 
water containing a few drops of HC1. 

Questions. (1) What result was obtained when each reagent 



NITROGENOUS ORGANIC COMPOUNDS OF PLANTS 221 

was added to the syntonin solution? (2) What was used in the 
preparation and what as the solvent for syntonin. (3) What is 
syntonin ? (4) What are the properties of syntonin? 

Experiment 63. — Preparation of vegetable casein from peas. 
Place in an evaporator, 1 gram of pea meal, 100 cc. H 2 0, and 3 cc. 
NaOH. Heat on the sand-bath, occasionally stirring. Filter. If 
the filtration is slow, pour off and use some of the clear solution. 
Neutralize with HC1 and observe. 

Questions.— (1 ) To what class of proteids does vegetable casein be- 
long? (2) What was used as the solvent for extracting the vegetable 
casein? (3) What effect had HC1 ? (4) How does vegetable 
casein resemble that from milk in solubility and other properties ? 

303. Peptones and Proteoses are closely related 
groups of proteids present in animal and vegetable bodies. 
When any proteid material is acted upon by the peptic 
and tryptic ferments, peptones are formed. These are 
soluble in water, and are not coagulated by heat or 
precipitated by acids or alkalies. They are derived from 
other proteids by ferment action, and are the first prod- 
ucts formed when the proteids of the food undergo diges- 
tion. In prepared or peptonized foods, the peptonizing 
process is carried on artificially. When meat undergoes 
the curing or ripening process, a small amount of peptones 
is produced. Peptones are naturally present in milk and 
also in traces in nearly all cereal products. When seeds 
germinate, proteoses are formed. These compounds are 
never present in ordinary foods in any appreciable amount. 

Experiment 64. — Tests with peptones. Measure into separate 
test-tubes, three 5 cc. portions of peptone solution. To the first, 
apply heat and, when cool, add a few drops of tannic acid. To the 
second, add a few drops of alum solution. To the third, add 5 cc. 
alcohol. The peptone solution is prepared by treating coagulated 



22 2 AGRICULTURAL CHEMISTRY 

egg albumin with pepsin. 5 grams of commercial pepsin are dis- 
solved in 1 liter of water containing 5 drops HC1. This artificial 
pepsin solution represents the solvent power of gastric juice upon 
proteid substances. The white of a hard boiled egg is put into a 
flask, and 250 cc. pepsin solution added ; the flask is then placed in 
a water-bath which is kept at a temperature of 38 C. for four or 
five hours. 

Questions, (r) What action did the pepsin have on the egg 
albumin and what was produced? (2) What was the result when 
heat was applied in test No. 1, and how does this compare with the 
result when egg albumin was similarly treated ? (3) What effect 
did tannic acid and alum have upon the pepsin solution and what 
did they produce? (4) What was the result when alcohol was 
added? (5) What are peptones ? (6) What does this experiment 
show in regard to some of the properties of peptones ? 

304. Insoluble Proteids. — The insoluble proteids are 
present in plant and animal bodies in larger amounts 
than are any of the other proteids, and include a large 
number of similar though chemically distinct bodies. 
Muscular tissue is composed largely of insoluble proteids. 
In seeds, the term gluten is frequently applied to this 
class of compounds which is a mixture of two or more 
insoluble proteids. Wheat gluten for example is com- 
posed of gliadin and glutenin. Gliadin is a glue-like body 
which binds together the flour particles, and in bread- 
making, enables the gas to be retained in the dough. 
Glutenin is a fine, gray material which unites mechanically 
with the gliadin to form gluten. An excess of gliadin 
produces a soft gluten. 

As a class, the insoluble proteids are not soluble in 
water or dilute salt solutions, but are soluble in dilute 
acids and alkalies. They all undergo the peptonizing 



NITROGENOUS ORGANIC COMPOUNDS OF PLANTS 223 

process and yield proteoses and peptones. The insoluble 
proteids are the most common form of proteids in foods. 
Experiment 65. — Obtaining insoluble proteids from oats. To 
the residue left in the flask from Experiment 60, add 2 cc. NaOH 
and 50 cc. water. After shaking and allowing half an hour (or 
until the next day) for the extraction of the proteids, filter off the 
solution and make the following tests: (1) Neutralize 5 cc. with 
HC1, and if no precipitate appears, add a few drops of lead acetate; 

(2) neutralize 5 cc. with HC1 and evaporate to dryness on the 
water-bath. 

Questions. (1) Why was NaOH used ? (2) What effect did the 
HC1 and lead acetate have when added to the solution, and what 
was formed? (3) How did this precipitate of insoluble proteids 
from oats compare in amount with the globulin and albumin 
precipitation in Experiments 59 and 60? (4) What is an insoluble 
proteid? 

305. Food Value of Proteids. — The proteid com- 
pounds of plant and animal bodies serve three purposes 
as nutrients : ( 1 ) To produce new muscular tissue and 
vital fluids in the body, and supply material for repairing 
broken-down tissue ; (2) to produce heat and energy ; 

(3) to assist in the production of fat. 

The main function of the proteids is to produce new 
proteid tissue in the body, and to furnish a material for 
the repair of old or worn-out proteid matter. The vital 
fluids of the body, as blood, chyme, milk, and the diges- 
tive fluids, all contain proteids, and the animal body is 
incapable of producing any from either non-nitrogenous 
or amide compounds. When the food fails to supply a 
sufficient amount of protein, the body uses its reserve 
supply as long as it lasts, and then starvation results. 
When there is an excess of proteids in the food, it is 



224 AGRICULTURAL CHEMISTRY 

used for producing heat or is stored up in the body as 
fat. Either an excessive or a scant amount of proteidsin 
a human or animal ration is not desirable or economical. 
As stated under chemical properties of proteids, Section 
298, the proteid molecule, when broken up, forms a large 
number of simpler bodies, as fatty acids and carbohydrate 
radicals ; hence, it is poor economy to feed proteids in 
excess and have part perform the functions of fats and 
carbohydrates. Protein is present in many foods in defi- 
cient amounts, and when such foods are used, they should 
be combined with those rich in proteids. There are a 
few proteids which are poisonous bodies. Some of the 
toxins produced during disease are proteids. 

306. The Amount of Proteids in Plants varies accord- 
ing to the kind, stage of growth, and part of the plant 
considered. Seeds always contain the largest amount, 
while roots and stalks contain the least. In wheat, oats, 
barley and rye, the amount ranges from 10 to 15 per cent., 
while in corn, it ranges from 9 to 12 percent. Beans 
and peas contain about 25 per cent. Clover hay contains 
from 11 to 14 per cent, ; timothy hay and corn fodder, 
6 to 9 per cent. ; while in straw there is usually less than 
4 per cent. During the early stages of growth, the dry 
matter in all plants is relatively richer in proteids than at 
maturity. This is because the proteids are formed mainly 
in the early stages, while the carbohydrates are produced 
more abundantly in the later stages of growth. 

307. Crude Protein.— This term is applied to the nitroge- 
nous compounds of foods, taken collectively, as a group. 
The word crude is used to distinguish this group because 



NITROGENOUS ORGANIC COMPOUNDS OF PLANTS 225 



it contains various nitrogenous bodies, not proteids. 
Pure protein is a simple chemical compound, while crude 
protein consists of a group of compounds of which pure 
protein is one. The albumin of eggs and milk and the 
gluten of grains are types of 
pure proteids. In many foods, 
as potatoes, roots, and fruits, 
less than half of the crude pro- 
tein is pure protein. Crude pro- 
tein, from different sources, is 
unlike in character, composition, 
and, to a certain extent, in food 
value. Less is known of its 
composition and food value than 
of any other class of nutrients 
in foods. 

In the analysis of plant and 
animal substances, the chemist 
first determines the per cent, of 
total organic nitrogen and then 
multiplies this by 6.25 to obtain 
the equivalent amount of crude 

protein. This is because the Fig. 81.— Digestion apparatus 

used in the determination of 

proteids contain, on the average, nitrogen, 
about 16 per cent, nitrogen, or there is about one part of 
nitrogen to every 625 of protein (100-^16 = 6.25). 
The nitrogen can be determined with accuracy ; in fact, 
the method for its determination is one of the most accu- 
rate in chemistry. In brief, the method consists in first 
digesting a small weighed amount of material in a flask 




226 



AGRICULTURAL CHEMISTRY 



with sulfuric acid to oxidize the organic matter and con- 
vert the nitrogen into ammonium sulfate (see Fig. 81). 




Fig. 82. — Distillation apparatus used in the determination of nitrogen. 

The nitrogen, in the form of ammonium sulfate, is then 
liberated as free ammonia, distilled and its amount deter- 
mined (see Fig. 82). 

Albuminoids 

308. Composition of Albuminoids. — This term is 
applied to a class of bodies resembling proteids, but 
differing from them in composition and food value. 
Albuminoids are found in both animal and plant bodies, 
but more abundantly in animal tissues. Some albumi- 
noids are composed of carbon, hydrogen, nitrogen, and 
oxygen, while others contain, in addition, phosphorus, 
sulfur and other elements. 

309. Nuclein is an albuminoid found in both plant 
and animal bodies ; it is the material of which the nuclei 
of cells are composed, and has been separated from milk, 
the yolk of egg, and white blood corpuscles, as well as 



NITROGENOUS ORGANIC COMPOUNDS OF PLANTS 227 

from plant substances. This albuminoid contains phos- 
phorus, and has been assigned the formula C^H^NgPjO^. 
Nuclein takes an important part in the growth and life 
processes of both plant and animal cells. From different 
sources it has slightly different chemical properties. It 
is probably a mixture of several bodies, and not a dis- 
tinct chemical compound. 

310. Gelatin is an albuminoid obtained from connec- 
tive tissue and bones by the action of either boiling 
water or dilute acids upon an albuminoid called collagen. 
Commercial gelatin or glue is the crude product obtained 
from animal refuse. The formula C 102 H 151 N 32 O S9 has been 
assigned to gelatin. Gelatin contains no sulfur, and has 
a different proportion of nitrogen from that found in 
proteid bodies. 

311. Mucin is an albuminoid present in connective 
tissue. It is the chief constituent of mucus, and imparts 
sliminess to the secretions of the mucous membrane. 
Mucin is present in the saliva from the submaxillary 
glands, and in the bile and other fluids of the body, par- 
ticularly those of an alkaline nature. 

312. Elastin is an insoluble albumoid found in connec- 
tive tissue. Keratin is the hard, horny material found 
in nails, hoofs and horns, while chondrin is obtained from 
cartilage. A number of other albuminoids also are pres- 
ent in both animal and plant bodies. 

313. Food Value of Albuminoids. — Gelatin and 
most of the animal albuminoids undergo digestion, but 
cannot take the place of protein in a ration. An animal 



228 AGRICULTURAL CHEMISTRY 

would soon die if its nitrogenous food were entirely in 
the form of gelatin. Gelatin, when combined with other 
nutrients, may, however, prevent the rapid conversion of 
the tissue proteids into circulatory proteids, and thus 
aids in establishing a proteid equilibrium in the body. 
Nuclein and some of the nucleated albuminoids have a 
higher food value than gelatin, and are considered as 
having the same value as the true proteids. As a 
nutrient, the gelatin albuminoids conserve the proteids 
of the body, but do not take the place of proteids in the 
repair of worn-out tissues. 

Amides and Amines 
314. Composition and Properties. — The amides and 
amines are heterogeneous compounds found in both 
animal and plant bodies. They are less complex in com- 
position than either the proteids or albuminoids and are 
produced by replacing one or more of the h3'drogen atoms 
of ammonia with an organic radical. If the radical is 
acid in character, an amide is formed ; if alcoholic or 
basic, an amine is produced. Amides and amines are re- 
lated to ammonia as will be observed from the following 
formulas : 

/H •C 2 H g 2 /CH„ 

N— H N— H N— H 

\h ^h Nh 

Ammonia. Amide. Amine. 

( Amidoacetic acid. ) ( Methylamine. ) 

When the methyl group or radical replaces one of the 
hydrogen atoms of NH 3 , the product is methylamine. 
When the acetic acid radical replaces one of the hydrogen 



NITROGENOUS ORGANIC COMPOUNDS OF PLANTS 2 29 

atoms of NH 3 , the product is amidoacetic acid. The 
amides and amines are sometimes called compound am- 
monias, and are produced in plants from ammonia during 
growth, and in animals during the digestion of proteids. 

315. Formation and Occurrence in Plants. — The 
amide and amine compounds in plants are present mainly 
in the early stages of growth. The young plant takes 
up from the soil simple nitrogenous compounds, as am- 
monia, then a chemical change occurs in the tissues of 
the plant, and as a result, a part or all of the hydrogen 
of the ammonia is replaced, and an amide is formed. In 
the study of the composition of proteids (see Section 295) 
it was stated that the proteid molecule when decomposed 
yields amide and amine products; consequently it would 
appear that these compounds are intermediate products 
in the production of proteids. In the early stages of 
plant growth, amides are present in greatest abun- 
dance, but as the plant approaches maturity, they are 
used for the production of proteids. In clover, for 
example, 35 per cent, of the total nitrogen is in the form 
of amides before bloom, while only 12 per cent, is in the 
same form after bloom. 

316. Formation and Occurrence of Amides in Ani- 
mals. — In the animal body, amides and amines are not 
formed from ammonium compounds, as in plants, but 
from proteids. When the proteid molecule is broken up, 
as in digestion, amides and amines are produced. Urea, 
an amide, is one of the final products in the digestion of 
protein, and is excreted from the body in the liquid ex- 
crements, while amidoacetic acid is excreted with the 



230 AGRICULTURAL CHEMISTRY 

solid excrements. The animal body cannot produce 
proteids from amides, or amides from ammonia. This 
elaboration or construction process can take place only in 
the plant. The animal body can simply make over into 
other forms, the proteids supplied in the food, or decom- 
pose them and form amides and other products. 

In animal tissues, many amides are produced during 
fermentation and decay, as methylamine, the base which 
gives the characteristic odor of fish. Methylamine is also 
found in rye fodder when the plant is at the heading-out 
stage, and imparts a fishy taste to the milk of cows fed 
upon such fodder. In meats, these compounds are 
associated with other bodies, as ptomaines, which are of 
a poisonous nature. Amides are also produced during 
the digestion of food, and if the intermediate products 
between proteids and amides are not completely oxidized, 
poisonous substances are formed. 

317. Food Value of Amides. — The amides do not 
have a high food value compared with the proteids, and 
cannot replace proteids in a ration. The amides possess 
only a secondary food value, and, like the gelatin albu- 
minoids, may to a limited extent prevent a rapid waste of 
body tissue. Some give taste and character to foods, as 
asparagin in asparagus, and in meats they are the bodies 
which give flavor. Some of the amides have medicinal 
properties, while others are poisonous. 

318. Amount of Amides in Foods. — In matured, 
grains, less than 5 per cent, of the total nitrogenous 
matter is in the form of amides, and in meats there is 
less than 1 per cent. In some foods, notably roots and 



NITROGENOUS ORGANIC COMPOUNDS OF PLANTS 23 1 

tubers, the amides constitute a third or more of the nitroge- 
nous matter. In fodders, the amount depends upon 
the stage of growth at which the crop is cut. When 
mature, from 10 to 15 per cent, of the nitrogenous matter 
is in the form of amides, while in the early stages of 
growth, there are two or three times as much. The 
amides and amines form a part of crude protein (see 
Section 307). In comparing the crude protein content 
of food, the amount of amide nitrogen should be con- 
sidered, because the amides are of less food value than 
the proteids. 

319. Protein Production and Disintegration. — The 

following cycle of changes takes place in the production 
of proteids in plants : 

(1) Ammonia is taken from the soil. 

(2) An amide is produced from ammonia. 

(3) A proteid is finally formed from the amide. 
When plants are used as food, the reverse order of 

changes takes place in the animal body : 

(1) The proteid of the food undergoes digestion, and 
is made over into proteid tissue in the body. This pro- 
teid tissue is finally broken up into amides. 

(2) The amide- is expelled from the body as waste 
matter. 

(3) In the soil, the amides are changed to ammonia, 
and are then ready to begin anew this cycle of changes. 

Alkaloids 

320. General Composition. — The alkaloids are nitroge- 
nous organic compounds present in many animal and 



232 AGRICULTURAL CHEMISTRY 

plant bodies, but not found in any appreciable amount in 
food plants. They are basic in character and unite with 
acids to form salts, just as ammonia unites with acids 
to form salts. Quinin, for example, in an alkaloid, and 
with sulfuric acid yields quinin sulfate. Animal alka- 
loids are sometimes called ptomaines and leucomaines. 
The vegetable alkaloids are generally named from the 
species of plant or source from which they are obtained, 
as Peruvian bark alkaloids, lupine alkaloids, and opium 
alkaloids. 

321. Plant Alkaloids. — No alkaloids are found in 
cereals or ordinary food plants, though at one time it 
was supposed that oats contained such a stimulating 
body to which the name avenin was given; later investi- 
gations have shown that there is no avenin or alkaloidal 
body in oats. The alkaloids chemically are closely 
related to the amines, and are produced by the action of 
amido compounds upon other bodies. They are also 
produced by the action of fungus bodies, as eargotin, the 
alkaloid from eargot or grain smut. While found most 
abundantly in the leaves and seeds, they are found in all 
parts of plants. Some are cultivated for these bodies 
which possess medicinal properties. Many poisonous 
weeds contain alkaloids as the water hemlock and 
monk's hood. Large numbers of alkaloids are known, 
and since they possess medicinal rather than food value, 
they are of more importance to the medical and pharma- 
ceutical than to the agricultural student. A few of the 
more common alkaloids and their sources are : 

Piperine, from seeds of black pepper. 



NITROGENOUS ORGANIC COMPOUNDS OF PLANTS 233 

Sinapore, from seeds of mustard. 
Vicine, from seeds of vetch. 
Nicotin, from leaves of tobacco. 
Quinin, from peruvian bark. 
Strychnin, from strychnos bean. 
Brucine, from str3 7 chnos bean. 
Morphin, from opium (seeds of poppy). 
L,upinin, from lupin seeds. 

322. Animal Alkaloids. — In the animal body alka- 
loids are produced by ferment action. During disease, 
and when the proteids of the food fail to undergo the 
natural chemical changes of digestion, alkaloids, or 
ptomaines, are produced which are active poisons or toxic 
bodies. When animal tissue undergoes decay, ptomaines 
are produced as the result of ferment action. In stale 
meat, fish, and cheese, there are a number of such bodies. 

323. Food Value and Production. — The alkaloids 
cannot be regarded as nutrients as they possess no direct 
food value. Medicinally, many are valuable because of 
their action upon certain nerve centers. Some alkaloids 
lessen the value of foods because they prevent the nor- 
mal process of digestion. A few alkaloids have been 
produced in the laboratory by synthetic methods, and it 
is believed that in a short time all of the more important 
ones will be produced in this way. 

324. Mixed Nitrogenous Compounds. — There are a 
few nitrogenous organic compouuds present in foods 
which do not belong to any of the four divisions : Proteids, 
albuminoids, amides, and alkaloids. Such bodies are called 



234 AGRICULTURAL CHEMISTRY 

mixed nitrogenous compounds, and are closely related to 
both the nitrogenous and non-nitrogenous groups. 

325. Lecithin is a nitrogenous fat. It is soluble in 
ether, and has many of the characteristics of fats. It 
contains fatty acids in combination with nitrogenous bases 
and other bodies. It is present in milk, egg- yolk, and in 
small amounts in all of the cereals. 

326. Nitrogenous Glucosides. — There are a number 
of glucosides which contain nitrogenous radicals. These 
glucosides, when treated with acids, yield glucose and 
nitrogenous acid products. The nitrogenous glucosides 
and lecithin may be regarded as compounds which are 
intermediate in the classification of the organic com- 
pounds into nitrogenous and non-nitrogenous groups. 

327. General Relationship of the Nitrogenous Or- 
ganic Compounds. — A general relationship exists among 
the nitrogenous compounds similar to that among 
the non-nitrogenous (see Section 289). The amides and 
amines are the simplest in chemical structure of the 
nitrogenous compounds, while the proteids are the most 
complex. In plants, the amides are intermediate com- 
pounds formed in the production of proteids. The proteid 
molecule contains, with other bodies, amide and fatty acid 
radicals. Amide products are also obtained from the 
albuminoids. Thus it appears that the amides and amines 
form the basal structure of the nitrogenous part of the 
molecules of proteids, albuminoids, and alkaloids, and 
these compounds differ from each other chemically, 
according to the nature and kind of radicals in combi- 
nation with the different amide and amine compounds. 



CHAPTER XXV 
Chemistry of Plant Growth 

328. Seeds. — A. seed is an embryo plant surrounded 
by reserve food materials in the form of mineral matter 
and nitrogenous and non-nitrogenous compounds. 

329. Ash of Seeds. — The proportion of ash in seeds is 
small compared with that in other parts of plants. For 
example, the wheat kernel contains 2 per cent, and 
the straw 7 per cent.; corn contains 1.75 per cent, and 
the stalks 7 per cent. While seeds contain comparatively 
little ash, this ash is more concentrated in the essential 
elements than that of the other parts of plants. In the 
seeds are stored large amounts of phosphorus pentoxid, 
magnesia and potash (ash elements which are of most im- 
portance for the nutrition of the young plant), while in 
the straw are found the largest amounts of the non- 
essential mineral elements, as silicon, sodium and chlorin. 
The per cent, of the various ash elements in cereals and 
other seeds is given in Section 209. The amount of ash 
in seeds is quite constant, more so than in the stems, 
leaves or other parts of plants. In mature wheat, there 
is rarely more than 2.10 per cent, or less than 1.80 per 
cent. , while in the straw, the amount may range from 5 to 
9 per cent. Constancy of composition is a characteristic 
of the ash of seeds. 

330. Non-Nitrogenous Compounds of Seeds. — Starch, 
cellulose, and fat are usually the most abundant non- 
nitrogenous compounds in seeds. Small amounts of 



236 AGRICULTURAL CHEMISTRY 

other non-nitrogenous bodies, as sugar, gums, pentosans 
and organic acids, are also present. There is no regular 
law as to the way in which the reserve food is stored up 
in seeds. Even in the same family of plants, the nature 
of this reserve food may vary between wide limits. 
Starch forms the largest proportion of the reserve food of 
the cereals. In oil seeds, as flax, rape and mustard, fat 
is the main form of non- nitrogenous food. Since fat is 
about 2.25 times more concentrated in fuel value than 
starch, it follows that in oil seeds, a large amount of re- 
serve material is stored up in a small space. Oil seeds 
are, as a rule, small in size, but concentrated in both non- 
nitrogenous and nitrogenous food. The cellular tissue of 
seeds is composed of cellulose and pentosan materials. 
The amount of pure cellulose is generally small. 

331. Nitrogenous Compounds of Seeds. — The nitroge- 
nous compounds of seeds are present mainly in the 
form of insoluble proteids, as the glutens of the cereals. 
Small amounts of other proteids, as albumin, globulin and 
proteose, are also present, as well as some of the albumi- 
noids, as nuclein, and a small amount of amide com- 
pounds. In studying the carbohydrates, it was found 
that starch was present in regular organized forms called 
starch granules. In many seeds, particularly cereals, the 
proteids also are present in organized forms called 
aleurone grains. Under the microscope, the aleurone 
grains look like crystals. They are not true crystals 
because they are not built on a definite plan. An 
aleurone grain consists mostly of proteid matter enclosed 
in a nitrogenous envelope. The nitrogenous compounds 



CHEMISTRY OF PLANT GROWTH 237 

of seeds are stored up mainly in the germ or portion adja- 
cent to the embryo. The amount of nitrogenous mate- 
rial in seeds is, like the ash, quite constant in form and 
amount. 

332. Chemical Changes during Germination. — All 
of the food materials in seeds undergo chemical 
changes during the process of germination. The chief 
agents in bringing about these changes are the various 
kinds of soluble ferments which are always present in 
seeds. The more important changes can be summarized 
as follows : Cellulose is changed to soluble carbohydrates; 
starch is changed to soluble forms and then into dextrose 
bodies ; fat is changed to starch ; insoluble proteids are 
changed to proteoses and a small amount to amides. 
Organic acids are produced from both nitrogenous and 
non-nitrogenous compounds during germination. 

333. Change of Starch to Soluble Forms. — When 
seeds germinate, the starch is changed to soluble forms 
before it is utilized by the plantlet. During conversion 
of starch into soluble forms, the diastase ferment be- 
comes active, rendering the granulose soluble, and finally 
leaving nothing but a pitted cellulose skeleton which is 
also rendered soluble. The change of starch into soluble 
forms and dextrose bodies is brought about by the action 
of ferments, particularly diastase which is found in all 
seeds. During the process of germination, some of the 
starch is oxidized, and heat is produced. Not only 
starch, but other carbohydrates, as pentose and cellulose, 
likewise undergo similar change during germination. 

Experiment 66. — Reaction of germinating seeds. Fill a cylin- 



2 3 8 



AGRICULTURAL CHEMISTRY 




der with moist sawdust ; then place upon 
the sawdust between two blue litmus papers 
a few wheat seeds. Cover with a little of 
the moist sawdust. After germination, ex- 
amine the litmus paper. 

Questions. ( i ) What was the reaction of 
the rootlets upon the litmus paper? (2) 
How was the material which caused the re- 
action produced? (3) What does this sug- 
gest as to the solvent action of plant roots ? 
(4) How would the dry matter of the ger- 
minated seeds compare with that of the origi- 
nal seeds ? 

334. Change of Fats to Starch. — 

In germination, the fats are first broken 
up into fatty acids and then con- 
verted into starch, soluble carbohydrates as dextrin and 
invert sugars. It is estimated that 887 parts of fat will 
produce 1700 parts of starch by the simple addition of 
oxygen from the air. Ferment action causes this change 
to take place. In the oil seeds, about twice the amount 
of reserve food is stored in the same space in the form of 
fat as in other seeds in the form of starch. 

335. Change of Insoluble Proteids to Soluble Forms. 

— The proteid compounds of seeds, present mainly in 
insoluble forms, are converted by ferment action into 
soluble forms as proteoses. Some of the soluble pro- 
teids are broken down into amides which are then in con- 
dition to be transported through the plant tissues and 
used as building material. After passing through the cell 
walls, these compounds are reconstructed into proteids. 



CHEMISTRY OF PLANT GROWTH 239 

There is always a slight loss of nitrogen in the germina- 
tion of seeds. 

336. Germination of Seeds and Digestion of Food 
Compared. — The chemical changes which take place in 
the germination of seeds are similar to those which take 
place in the digestion of food. In the germination pro- 
cess, starch, fat, and proteids are changed by ferment 
action to soluble forms. The diastase and peptonizing 
ferments are among the most active in producing 
the chemical changes in both the germination and diges- 
tion processes. Seed germination is, in part, a digestion 
process. 

337. The Necessary Conditions for Germination 

are: (1) Moisture, (2) heat, and (3) oxygen. The 
same conditions which produce decay are necessary for 
germination. The temperature required for germination 
ranges between comparatively narrow limits : 

Wheat 35 F. to 104 F. 

Barley 38 F. to 104 F. 

Peas 44. 5 F. to 102 F. 

Cora 48 F. to 1 15 F. 

The necessity of oxygen for germination is shown by 
the following experiment : When seeds are put into 
water those that float are generally the only ones that 
germinate. A few of those that sink may germinate, 
getting their oxygen from that dissolved in water. If a 
current of air is passed through the water all of the seeds 
will germinate. Oxygen is necessary during germination 
in order to oxidize some of the reserve material and pro- 
duce heat. Seeds, in germinating, always lose weight. 



240 AGRICULTURAL CHEMISTRY 

Malted or germinated seeds weigh less than the original 
seeds. 

338. Heavy- and Light= Weight Seeds — While seeds 
are quite constant in chemical composition, there is, 
however, a slightly greater amount of total plant food in 
heavy- than in light-weight seeds. In the case of wheat, 
experiments have shown that the additonal reserve food 
in heavy-weight seeds favorably influences the growth of 
the crop, particularly when the soil is slightly deficient 
in available plant food. The additional reserve food in 
heavy-weight seeds enables the young plant to reach a 
higher stage of growth before being compelled to collect 
and assimilate food from the soil. When the soil is in a 
high state of fertility the difference in results between 
light- and heavy-weight seeds is less noticeable. 

Experiment 67. — Calculation of plant food in seeds. Weigh 
100 plump, well-formed wheat kernels. Then from this weight 
and the following data compute the grams of nitrogen, phosphoric 
acid and potash per 1,000 wheat kernels. Wheat contains about 
2 per cent, nitrogen, and 90 per cent, dry matter. The dry matter 
contains about 2 per cent, ash, approximately 50 per cent, of the 
ash being P 2 O s , and 33 per cent. K 2 0. Repeat the experiment, 
using 100 shrunken wheat kernels. Tabulate and compare the 
results. 

Questions. — (1) How much more reserve plant food is there as 
N, P 2 O s and K 2 in heavy- than in light-weight seeds? 

Movement of Plant Juices 

339. Joint Action of Chemical and Physical Agents. 

— The compounds produced in the leaves of plants are 
transported and stored in other parts, as the seeds or 
roots ; this is brought about by the joint action of 



CHEMISTRY OF PLANT GROWTH 24 1 

physical and chemical agents. This action can best be 
understood by first considering a few of the properties 
of plant tissues, as porosity, capillarity, and osmosis. 

340. Porosity of Tissues is a property common to all 
forms of matter, and one possessed particularly by vege- 
table substances. The living plant not only admits the 
passage of water through its tissues, but absorbs it until 
the pores are filled. Animal and vegetable tissues always 
possess the power to take up and tenaciously hold 
water within their fibers. This is, in part, due to capil- 
lary action (see Section 20, Chemistry of Soils and Fer- 
tilizers). Capillarity, assisted by evaporation, explains 
only in part the movement of the plant juices. Com- 
pounds formed within the leaf must be transported in an 
opposite direction to that taken by the sap in moving 
from the roots to the leaves. This movement is effected 
by osmosis, and chemical reaction within the cells. 

341. Osmosis — When a bottle filled with a solution of 
salt, colored with litmus, is placed in a large vessel of 
water, the bottle will discharge its contents into the 
water and the movement of the solutions can be followed 
with the eye. If sugar and salt solutions are separated 
by a membrane, there is a gradual interchange between 
the two solutions. Some of the sugar finds its way into 
the salt solution, and some of the salt finds its way into 
the sugar solution. This action or interchange is still 
further increased when the solutions are of different 
densities and when chemical action is taking place on 
both sides of the membrane. Such an action takes place 
in plant tissues, which are composed of a large number 



242 AGRICULTURAL CHEMISTRY 

of small cells, the walls of which serve in part, as mem- 
branes, and offer but little resistance to diffusion. The 
cells are filled with sap, which is acid in nature and con- 
tains numerous solid substances in solution. Between 
the cells are intercellular spaces filled with sap of differ- 
ent density from that within the cells and charged 
with numerous alkaline matters taken from the soil. 
Here, then, are nearly the same conditions as when the 
salt and sugar were separated, and the result, osmosis, is 
the same in each case. Within the cell walls active chem- 
ical changes are taking place which aid in this inter- 
change. It cannot be said that there is a constant flow of 
sap in any one direction, as blood flows in the animal body. 
It was formerly believed that there were two courses of sap 
in the plant, upward and downward. The movement of 
the plant juices is now considered as due to (i) capillary 
action, aided by evaporation which disturbs the equilib- 
rium of the plant juices, together with (2) osmosis aided 
by chemical action within the cells. These factors are, to 
a certain extent, mutually dependent upon each other. 
By their joint action, aided by the chemical changes 
within the plant, the water from the soil is taken into 
the plant through the roots with the mineral matter in 
solution, which serves as food, and finds its way all 
through the plant, finally returning to the roots charged 
with the material that can be made only in the leaf and by 
the aid of light and sunshine. 

Chlorophyl and Protoplasm 
342. Chemical Action in Leaves 5i Plants. — All of 
the organic compounds of plants are produced within the 



CHEMISTRY OF PLANT GROWTH 243 

cells of the leaves. The mineral food and nitrogen taken 
from the soil and the carbon dioxid from the air are 
chemically united in the cells of the leaves to form the 
various non-nitrogenous and nitrogenous compounds of 
plants. Chlorophyl and protoplasm are the two substances 
which take the most active part in the production of the 
organic matter. 

343. Chlorophyl is the name applied to the material 
which imparts the green color to plants. It is not a 
simple compound, but is composed of a number of closely 
related organic compounds. The chlorophyl body con- 
tains both organic and mineral matter. Chlorophyllan is 
one of the compounds obtained from chlorophyl. Iron, 
phosphorus and magnesium are among the more im- 
portant mineral elements necessary for the functional 
activity of the chlorophyl body. This mineral matter is 
combined with the organic compounds which form a part 
of the chlorophyl grain. Chlorophyl is contained in the 
active living cells of plants, but makes up only a small 
part of the contents of the cell. 

344, Protoplasm. — The chlorophyl body is suspended 
in a gelatinous, colorless liquid called protoplasm which is 
composed mostly of proteid and albuminoid materials. 
It is the living substance of the plant organism, and is 
the part which gives life and activity. In chemical com- 
position, it is exceedingly complex, and is composed of a 
number of proteids, albuminoids and other organic com- 
pounds. The protoplasm, aided by the chlorophyl, has 
the power of combining the food elements and producing 



244 AGRICULTURAL CHEMISTRY 

all of the organic compounds of the plant. Protoplasm 
is the living part of both plant and animal cells. 

345. Production of Chlorophyl. — When the plant cell 
is first formed, the protoplasm contains no green grains. 
Small, colorless grains first appear, and then the green- 
ing of these grains takes place. The chlorophyl body- 
may make its appearance in the absence of light, but the 
last stage of its development can take place only under 
the influence of light and at a higher temperature than 
is required for the first stage of the process. With a cool 
temperature, there is plant growth, but the vegetation 
looks yellow because there is not sufficient heat for the 
completion of the second part of the process of chlorophyl 
development. Chlorophyl is destroyed by intense light 
as well as by the absence of light. It is soluble in 
ether and alcohol and is one of the constituents of 
ether extract. The green color is easily destroyed, 
but the chlorophyl body is quite stable and resists the 
action of dilute acids and alkalies. Chlorophyl loses its 
activity, and undergoes a decided change in composition 
as the plant matures. Some of the elements which com- 
pose the chlorophyl, as nitrogen and phosphorus, are 
used for seed formation. At the time of the greatest 
amount of color in plants, there is the greatest cell 
activity and the largest amount of plant tissue is being 
produced. When a plant ripens, the decline of activity 
of the cells can be observed by the change in the color of 
the plant. When corn, for example, ripens, the lower 
joints of the stalk turn yellow first, indicating that 
growth and activity have ceased in those parts. Then 



CHEMISTRY OF PLANT GROWTH 245 

the upper leaves become yellow, and finally the husk be- 
comes yellow and inactive. Chlorophyl is one of the 
principal agents which takes an active part in plant growth, 
and whenever chlorophyl is destroyed, plant growth is 
checked. 

Experiment 68. — Extracting chlorophyl from leaves. Place in 
a test-tube, 0.5 gram of dry, green leaves. Add 10 cc. alcohol, shake 
vigorously and, after the alcohol is colored green, filter off the 
solution, and evaporate to dryness at a low temperature on the 
water-bath. 

Questions. — d) Describe the appearance of the chlorophyl 
residue. (2) What is chlorophyl ? (3) Of what is it composed? 
(4) What other solvents could be used in place of alcohol. 

346. Function of Chlorophyl. — The chief function of 
chlorophyl, aided by protoplasm, is the production of 
starch and other organic compounds in the cells of plant 
leaves. Chlorophyl alone cannot perform this function, 
but must be associated with, and aided by, protoplasm. 
Minute starch grains are sometimes found within the 
chlorophyl grains. The actual growth of starch within 
the chlorophyl body can be observed with the microscope. 
No other compounds have been found so organically con- 
nected with the chlorophyl grains as starch. If a plant 
is placed in darkness, both the starch and the coloring- 
matter in the plant cells disappear. The plant cell is the 
chemical laboratory in which the various organic com- 
pounds, as starch, sugar and proteids, are elaborated. 
From the cells in the leaves, they are transported to other 
parts of the plant as the seeds, roots or tubers, where they 
are stored up and serve as reserve food. 

347. Production of Organic Hatter. — By the joint 



246 AGRICULTURAL CHEMISTRY 

action of the protoplasm and chlorophyl within the plant 
cells, starch and all other organic compounds are pro- 
duced from the carbon dioxid of the air and from the 
water, mineral matter, and nitrogen of the soil. All of 
the carbohydrates can be produced from starch as was 
stated in Section 289, which discusses the general rela- 
tionship existing between the various non-nitrogenous 
compounds. Fat, as well as other non-nitrogenous com- 
pounds, is produced from starch. Proteids are produced 
from amides. By a succession of chemical changes, the 
amide molecule takes on fatty acid and carbohydrate 
radicals, and as a result, complex proteids are produced. 
All of these chemical changes take place within the plant 
cell ; and, for the production of the various compounds 
which constitute the dry matter of plants, the essential 
mineral elements, nitrogen in combination, carbon dioxid 
and water, are required. 



CHAPTER XXVI 
Composition of Plants at Different Stages of Growth 
348. Composition and Stage of Growth — Plants do 
not have the same chemical composition at different 
stages of growth. The chlorophyl and protoplasm are 
most active in the early stages and produce the nitrogenous 
compounds more rapidly than the non-nitrogenous ones. 
The later stages of growth are utilized mainly for the 
production of carbohydrates and for the various chemical 
and physical changes incident to ripening and the transfer 
of the organic compounds from the leaves to the seeds. 
Plants have a different food value at their different 
stages of growth as well as a different chemical composi- 
tion. 

340. Assimilation of flineral Food by the Wheat 
Plant. — The various elements of plant food utilized by 
spring wheat are assimilated quite rapidly in the early 
stages of growth. The mineral matter being essential for 
the production of the organic compounds is taken from 
the soil in advance of their formation. Before the crop 
has completed the first half of its growth, over 75 per 
cent, of the total mineral matter has been taken from the 
soil. Of the mineral elements, phosphoric acid, potash 
and lime are assimilated most rapidly. 

350. Assimilation of Nitrogen by the Wheat Plant. 

— The nitrogen utilized by the spring wheat crop is 
taken from the soil in advance of the mineral matter. 



248 AGRICULTURAL CHEMISTRY 

Nitrogen is assimilated by the plant more rapidly than 
any of the elements which form a part of the organic 
compounds. When the plant has completed half its 
growth, under normal conditions about 85 per cent, of 
the total nitrogen required by the crop has been taken 
from the soil. This is one reason why nitrogen and the 
essential ash elements should be present in the soil in 
available and liberal amounts for a wheat crop. When 
the largest amount of any element or compound is taken 
as 100, the corresponding amounts present during the 
different stages of growth of the wheat plant are as 
follows : 

Wheat, 50 Wheat, 65 Wheat, 80 Wheat, 

days, before days, headed days, milk harvest 
heading out. out. state. time. 

Total dry matter 46 59 95 100 

Organic matter 44 57 90 100 

Total nitrogen 86 89 96 100 

Potassium oxid 45 88 100 94 

Calcium oxid 67 91 100 96 

Magnesium oxid 57 68 99 100 

Phosphoric anhydrid. •• . 80 83 98 100 

351. Clover; Rapidity of Growth. — In clover, the same 
general order of changes occurs at the different stages of 
growth as in wheat, but as the two plants are so unlike, 
clover being a biennial and a legume, and wheat an 
annual and a grain, the rapidity of growth and formation 
of organic compounds in the two plants are naturally 
dissimilar. The largest amount of the dry matter in 
clover is produced between early and full bloom. During 
this period about 60 per cent, of the organic compounds 
are formed. As in the case of wheat, the nitrogenous 




Plate III.— Clover roots. 



PLANT GROWTH AT DIFFERENT STAGES 249 

compounds are formed more rapidly and in advance of 
the non-nitrogenous ones. At the time of early bloom, 
about 37 per cent, of the total nitrogenous compounds 
have been formed, but the crop at this stage of develop- 
ment has only 31 per cent, of the total organic com- 
pounds produced during growth. When clover is very 
young, before the flower head is visible, only about 10 
per cent, of the organic compounds have been produced, 
but this organic matter is rich in nitrogenous compounds 
as it contains about 15 per cent, of the total amount 
assimilated by the crop; a large share of this nitrogen, 
however, is in the form of amide compounds. The com- 
position of the leaves and stems, at the different stages 
of growth, show that, at first, the leaves contain about 
2.5 times as much nitrogenous matter as the stems, 
while at maturity, there is less than twice as much. 
At the time of full bloom, the largest amount of nitroge- 
nous matter is present, and it is then in the form of pro- 
teids to the extent of about 88 per cent. In the last 
stages of growth, there is also a notable increase in the 
content of crude fiber. The differences in composition 
and feeding value between clover, cut and cured in full 
bloom, and at maturity are as follows: 

Clover at full bloom, 
i. The crop contains less fiber 4. The nutrients in the crop are 
than when mature. more evenly distributed. 

2. The crop contains its maxi- 5. The crop contains its maxi- 

mum amount of proteids. mum amount of essential 

3. A smaller yield per acre is oils, which impart palata- 

secured than at maturity, bility. 

but the crop is more con- 6. The nutrients in the clover 

centrated in protein. are more digestible. 



250 AGRICULTURAL CHEMISTRY 

Clover when ripe, 
i. The crop contains a larger 4. Some of the nutrients in the 
amount of fiber. crop are transferred to the 

^, , . t, seeds, leaving less in the 

2. The crop contains a smaller ° 

. stems 

per cent, of protein than . 

, . , „ , , 5. At maturity, there are less 

when in full bloom. ° „ „ -" 

of the essential oils than at 

3. A larger yield per acre is any other period. 

secured, and the crop is 6. At maturity, the crop is less 
more concentrated in car- digestible than at full 

bohydrates. bloom. 

Composition of Clover at Different Stages of Growth. 

Flower head Early Full End of 

invisible. bloom. bloom. flowering. Ripe. 

Per cent. Per cent. Per cent. Per cent. Per cent. 

Water 86.00 85.59 74.96 7 x - 6 5 33-47 

Dry matter 14.00 14.41 25.04 28.35 66.53 

Composition of the Dry Matter. 

Ash 10.57 10.22 6.85 7.02 6.21 

Ether extract 5.35 4-7° 5-73 4-26 3.92 

Crude protein ... 23.61 17.19 14.81 14.40 14.06 

" fiber 13.37 20.08 24.62 25.28 26.60 

Nitrogen-free ex- 
tract 47- to 47.81 47.99 49.04 49.21 

Composition of the Dry Matter of the Leaves and Stems. 

Flower head invisible. Early bloom. Third period. 

Leaves. Stems. Leaves. Stems. Leaves. Stems. 

Per cent. Per cent. Per cent. Per cent. Per cent. Per cent. 

Ash 10.02 11.02 10.07 11.30 9.19 4.87 

Crude protein 30.68 13.44 27.38 11.25 19-37 IJ - 26 

fiber... 10.48 18.46 10.51 26.32 15.36 35.27 

When the largest amount of any compound in the crop 
is taken as 100, the percentage amounts at the different 
periods of growth are as follows : 



PLANT GROWTH AT DIFFERENT STAGES 25 1 

Flower head Early Full End of 

invisible. bloom. bloom. flowering. Ripe. 

Percent. Percent. Percent. Percent. Percent. 

Dry matter 9 31 97 100 97 

Total ash 14 46 98 100 95 

Total nitrogen 15 37 100 96 94 

Proteid nitrogen 67 70 88 85 83 

Fiber 5 24 92 96 100 

Potassium oxid 15 50 100 94 86 

Calcium oxid 15 37 97 100 97 

Magnesium oxid 8 35 100 92 91 

Phosphoric anhydrid- 14 34 98 100 98 

(These tables are from Minn. Expt. Sta. Bull. 34.) 

352. Flax; Rapidity of Growth. — The flax plant has a 
short growing period, about seventy days, and the plant food 
is assimilated at a rapid rate. Before the time of bloom, 
the nitrogenous material and mineral matters have been 
absorbed in quite large amounts. When 40 per cent, of 
the nitrogenous matter has been produced, the flax plant 
contains 55 and 60 per cent., respectively, of its total 
nitrogen and mineral matter. At the time the flax is in 
full bloom, 75 per cent, of the organic compounds have 
been formed. After seed formation begins, there is no 
nitrogen or mineral matter taken from the soil. Flax is 
very rich in nitrogen, containing even more than clover. 
This is one of the few crops in which the ash in the seed 
exceeds that in the straw; the seed contains about 3.75 
per cent, ash, while the straw contains less than 3 per 
cent. The oil in the seed is produced mainly from starch 
in the later stages of growth. Between full bloom and 
maturity, less than 25 per cent, organic matter is pro- 
duced. The rate of formation of the organic matter and 



252 AGRICULTURAL CHEMISTRY 

assimilation of the elements from the soil are given 
in the following table : 

Before In full Seeds well 

bloom. bloom. formed. Ripe. 

Percent. Percent. Percent. Percent. 

Total organic matter 40 75 95 100 

Ash 60 88 100 98 

Total nitrogen 55 80 100 98 

Calcium oxid 32 64 98 100 

Potassium oxid 55 90 100 95 

Phosphoric anhydrid 35 70 98 100 

Minn. Expt. Sta. Bull. 47. 

Maize (Corn) 

353. Importance. — Since Indian corn or maize is grown 
over such a wide range of territory, and is used alike as 
animal and human food, and as animal food may serve as 
either grain or forage, a knowledge of the chemical changes 
which take place during its growth, and the composition 
of the plant at maturity, will enable the student to utilize 
this crop more economical^ 7 in the feeding of farm 
animals. Some of the facts relating to the composition 
of corn at different stages of growth and the analyses 
given in this chapter are taken largely from Bulletin No. 
9, Mo. Agr. Expt. Station. 

354. Roots. — The function of the roots is to collect 
and assimilate and transport to other parts the nitrogen 
and mineral food from the soil. In mature corn, but a 
small amount of the essential elements of plant food are 
present in the roots, only sufficient for the structure of the 
root tissues. During growth, there is always some being 
transported to the parts above ground. At maturity, the 
dry matter in the roots constitutes about 5 per cent, of 



PI.ANT GROWTH AT DIFFERENT STAGES 253 

the dry matter of the plant. The roots contain the 
largest amount of fiber and the smallest amount of fat of 
any part of the plant. Of the ash elements, soda is 
present in greater amounts than in parts above the ground. 
In the early stages of growth, the roots are very rich in 
iron, which decreases as the plant matures, because of its 
being given over to other parts. The nitrogen in the 
roots never, at any stage of growth, exceeds 1.25 per 
cent, of the dry matter. It is transported to the parts 
above ground more rapidly than any other element. 
During the last fifteen days of growth, there is but little 
mineral food, except magnesia, taken up, and there is a 
loss of about 12 per cent, of potash from the roots which 
indicates that the retrograde movement of potash at 
maturity may extend from the roots back to the soil. In 
the later stages of growth, there is a great influx of mag- 
nesia. Silica and the non-essential ash elements make 
up the larger portion of the ash elements in the mature 
plant. 

355. Stalk. — The stalk, during growth, undergoes a 
decided change in composition ; there is a gradual in- 
crease in the content of fiber and a decrease in proteids. 
The outside of the stalk has a different chemical com- 
position from the pith. The largest per cent, of dry 
matter is found in the stalks from two to three weeks 
before maturity. As the plant matures, the proteid and 
circulatory carbohydrates are transferred to the seed. 
When mature, both the pith and stalk have a low protein, 
fat and digestible carbohydrate content, and hence a low 
feeding value. The pith is somewhat richer in nitroge- 



254 AGRICULTURAL CHEMISTRY 

nous matter than the stalk. The ash of the stalk is 
characteristically rich in silica. 

356. Leaves. — Since all of the chemical compounds of 
the plant are first produced in the leaves, and then trans- 
ported to other parts, it follows that the leaves at different 
stages of growth have a variable composition. Since the 
cells of the young leaves contain more protoplasm than 
mature leaves, the largest amount of nitrogenous matter 
is present there in the early stages of growth. As the 
plant matures, this nitrogenous matter is given up for the 
formation of other parts, and then there is a decline in the 
percentage amount of nitrogen in the leaves. The largest 
amount of dry matter in the leaves is found about six 
weeks before maturity. The plant as a whole, however, 
increases even more rapidly in dry matter after this 
time, but no additional organic matter accumulates in the 
leaves but is used for seed formation. As the plant 
matures, the total ash in the leaves steadily increases, due 
to silica, which is deposited there as inert material, while 
that in the stems declines. As the plant matures, the 
phosphorus content of the leaves declines, the phosphorus, 
like the nitrogen, being stored up in the seeds. The 
largest amount of potash in the leaves is at the time of 
the largest amount of dry matter, about six weeks before 
maturity. Next to the seed, the leaves contain the 
largest amounts of protein, fat, and digestible carbohy- 
drates of any part of the plant. When green, the leaves 
have a higher nitrogen content than when yeilow. The 
feeding value of corn fodder depends to a great extent 
upon the condition of the leaves. 



PLANT GROWTH AT DIFFERENT STAGES 255 

357. Tassel. — The tassel has some of the chemical 
characteristics of the seed ; it is concentrated in nitrogen, 
has less fiber, and an ash rich in phosphates. The flower 
stalks and anthers yield an ash in composition like that of 
the stems, while the ash of the pollen is nearly identical 
with that of the matured grain. The pollen is par- 
ticularly rich in nitrogen. One of the claims made for 
detasseling corn, is to prevent loss of nitrogen and phos- 
phoric acid through the pollen. It is estimated that the 
nitrogen removed in the pollen amounts to from 5 to 
10 pounds per acre. The fresh and dried silk (stigmas) 
shows a decline in both nitrogen and phosphoric acid 
after fertilization. 

358. Husk. — The husk when first formed has all of the 
materials for the development of the seed, and its compo- 
sition at different stages of growth shows a gradual trans- 
fer of its constituents to the ripening grain. When fully 
mature, the husks are much poorer in ash and nitrogen 
than the leaves or stems, but are not so poor as the cob. 
The cob remains functionally active longer than any other 
part of the plant, and is composed largely of cellulose and 
pentose compounds, and contains but little protein or fat. 

359. Ripening Period.— The corn plant, at first, absorbs 
its mineral food and nitrogen at a very rapid rate. In fact, 
there is but little mineral matter or nitrogen assimilated 
during the last few weeks of growth. The last stage of 
development is a period of rearrangement and transporta- 
tion of the compounds from the leaves to the seed. The 
composition of the different parts of the corn plant when 
mature and of the ash is given in the following table : 



256 



AGRICULTURAL CHEMISTRY 



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CHAPTER XXVII 

Factors Which Influence the Composition and 

Feeding Value of Crops 

The main factors which influence the composition and 
feeding value of crops are: (i) Seed, (2) soil, (3) cli- 
mate, (4) stage of maturity, (5) method of preparation 
as food, and (6) combination with other foods. 

360. Seed. — The composition and individuality of the 
seed influence the composition and feeding value of the 
forage crop produced. Heavy-weight seeds are usually 
more mature and contain a larger amount of reserve plant 
food than those of light weight (see Section 338). Ex- 
periments by Heilreigel show that the heavier the seed, 
the more vigorous the young plant. Where there was 
not an overabundance of plant food in the soil, the differ- 
ence in vigor of plants was discernible even up to the time 
of harvest. Experiments at the Illinois Station (Bull. 
Nos. 53 and 55 ) show that by careful selection of seed 
corn, the percentage amount of nitrogenous matter in the 
grain may be increased from 0.5 to 1.25 per cent. Not 
all of the cereals respond as does corn to the influence of 
seed selection to produce variations in chemical compo- 
sition. 

The care and storage which the seed receives prior to 
planting also influences its vitality. When seed corn is 
stored in a damp or poorly ventilated place, the excessive 
amount of moisture results in injuring the vigor of the 
germ. Seed wheat is often injured by being stored in 



258 AGRICULTURAL CHEMISTRY 

elevators where bin-burning caused by fermentation takes 
place. Sound heavy seeds of full maturity always give 
the best crop returns. Forage crops are more susceptible 
to seed influences than are grain crops, because the leaves 
and stems of plants are less constant in composition than 
is the seed. 

361. Soil. — The condition of the soil as to available 
plant food has a material influence upon composition, and 
in promoting a balanced crop growth. Experiments 
conducted at the Connecticut Experiment Station (Storr's 
Annual Reports, 1898, 1899) show that fodder crops grown 
with a liberal supply of nitrogen have a tendency to con- 
tain more of the nitrogenous compounds than similar 
crops grown with a scant supply. The nitrogen and 
available mineral matter increase the activity of the pro- 
toplasm and chlorophyl in the production of all of the 
organic compounds. With a larger amount of available 
plant food, particularly nitrogen, a larger amount of 
foilage is produced. All foliage crops, grown upon rich 
soils, have larger leaves and a higher nitrogen content 
than those grown on poor soils. 

The condition of the soil influences the composition of 
leaves and stems to a greater extent than it does the com- 
position and character of the seeds because they are more 
constant in composition. The selection of seed corn has 
a greater influence upon the composition and feeding 
value of corn fodder than it has upon the grain. Fodder 
crops, produced upon fertile soils and under favorable 
climatic conditions have the highest feeding value. The 



FEEDING VALUE OF CROPS 259 

condition of the soil, as to acidity or alkalinity, also in- 
fluences the character and composition of crops. Crops 
produced upon acid soils have a different appearance from 
those grown upon mildly alkaline soils. An unbalanced 
condition of plant food in the soil produces an unbalanced 
crop growth. It is not possible, however, by the use of 
manures or the selection of seeds, to entirely change the 
composition of crops. In the extensive experiments by 
Eawes and Gilbert (Rothamsted Memoirs, Vol. Ill), the 
continued use of nitrogen and mineral manures for a 
period of twenty years showed no material increase in the 
amount of nitrogenous matter in the wheat. In similar 
experiments with potatoes, in which nitrogenous ma- 
nures alone were used, there was an increase of 0.05 per 
cent, of nitrogenous matter. The sugar-beet has been 
extensively changed in composition by cultivation. The 
content of sugar has been increased from 8 to 16 per 
cent. Wheat and other grains show material differences 
in weight and composition when grown upon different 
types of soil. Experiments have been made where wheat 
grown from one lot of seed under different climatic and 
soil conditions showed a difference of 18 bushels per acre 
in yield, and 8 pounds per bushel in weight (Minn. 
Expt. Sta. Bull. No. 23). Forage crops produced upon 
soils of high fertility have a higher feeding value than 
crops grown upon poor soils. At the Minnesota Experi- 
ment Station, timothy and corn fodder grown on land 
that had been manured and rotated, and similar crops 
grown on unmanured land showed the following amounts 
of protein : 



260 AGRICULTURAL CHEMISTRY 

Timothy hay grown on Corn fodder grown on 

manured un manured manured unmanured 

land. land. land. land. 
Per cent. Per cent. Per cent. Per cent. 
Crude protein (dry- 
matter basis) ... 8.75 6.45 8.85 6.32 

362. Climate. — In the early stages of plant growth, the 
nitrogenous compounds are produced more abundantly 
than are the non-nitrogenous (Section 351). If the 
growing season is in any way cut short, the crop has a 
slightly larger amount of nitrogenous matter than if 
normal conditions prevail. Any shortening of the grow- 
ing period or forcing of the crop to maturity lessens the 
per cent, of dry matter, increases the nitrogenous com- 
pounds, and decreases the carbohydrates. The composi- 
tion of grains is influenced by climatic conditions, particu- 
larly at the time of seed formation when growth is 
often checked before all of the compounds have been 
transferred from the leaves to the seeds ; shrunken or 
immature grain is the result. Such grain contains less 
starch and more nitrogenous compounds than that which 
has fully matured. Experiments with potatoes by L,awes 
and Gilbert show that they too are, to a slight extent, 
influenced in composition and starch content by climatic 
conditions ; the longer the growing period, the larger the 
amount of starch. A short and forcing growing season, 
together with a fertile soil, has a tendency to produce 
crops of high nitrogen content. 

363. Stage of flaturity — Since all crops at first pro- 
duce nitrogenous compounds in larger amounts than at 
later stages, it follows that early cut crops contain pro- 
portionally more nitrogen than those cut later. This in- 



FEEDING VAEUE OF CROPS 26 1 

crease in nitrogenous matter is, however, at the expense 
of the total dry matter in the crop. If crops are cut too 
early, that is, before early bloom, too much of the nitro- 
gen is in the form of amides, some of which are changed 
to proteids at a later stage. Early cutting results in 
securing a smaller yield per acre of dry matter more con- 
centrated in nitrogenous compounds. When fodder crops 
are cut at early or full bloom, the nutrients are more 
evenly distributed than at maturity when some of the 
proteids and carbohydrates have been transferred from 
the leaves to the seeds, leaving stems and leaves with a 
larger amount of fiber and less protein. The composi- 
tion and comparative feeding value of clover cut at 
different stages of growth are given in Section 351. 

364. flethod of Preparation as Food. — The method of 
curing and preparing a fodder affects its food value. 
Overdrying causes a mechanical loss of leaves which 
gives the fodder a different composition and feeding 
value from that when the leaves are all secured. Bleach- 
ing results in partial destruction of the chlorophyl and a 
loss of the essential oils that impart palatability. Other 
chemical changes which have a tendency to make the 
fodder less digestible also take place. A mechanical 
loss of leaves and exposure to leaching rains result in a 
loss of nutritive value. The materials extracted are the 
most soluble and digestible. A heavy, leaching rain may 
extract 10 per cent, or more of the nutrients, making the 
leached fodder less available and less palatable. 

The method of storing and the mechanical condition of 
a fodder also influence, to a limited extent, the avail- 



262 AGRICULTURAL CHEMISTRY 

ability of the nutrients. The influence which the com- 
bination of fodders has upon digestibility and food value 
is discussed in Chapter XXXV. 

365. Improving the Feeding Value of ForageCrops. — 

The main factors, as seed, fertility of soil, stage of 
maturity, and care which the fodder receives, are all 
under the control of the farmer, climate being the only 
factor that is not directly controllable. Lack of moisture 
in dry seasons can, however, in part, be overcome by 
shallow cultivation. By careful selection of seed, con- 
serving the fertility of the soil, and suitable methods of 
cultivation and storage, it is possible not only to increase 
the yield but also to change the chemical composition and 
feeding value of forage crops. As yet, experiments have 
not demonstrated the extent to which all crops are sus- 
ceptible to these influences. 



CHAPTER XXVIII 
Composition of Coarse Fodders 

366. The Term Coarse Fodders is applied to animal 
foods which usually contain large amounts of crude fiber, 
and, while bulky in nature, are essential foods, many of 
them having a high nutritive value. A coarse fodder 
may be either green or field-cured ; pasture grass, timothy 
hay, and corn fodder are all examples of coarse fodders. 
The proteid content of coarse fodders ranges from 4 per 
cent, and less, in straw, to 12 per cent, and more, in 
clover and legumes. 

367. Straw. — The straw from wheat, oats, barley, and 
rye contains from 36 to 38 per cent, of crude fiber, and 
less than 4 per cent, of crude protein, oat straw being the 
richest. The amount of fat in straw is small, rarely exceed- 
ing 1.5 per cent. Straw contains from 6 to 9 per cent, 
of water. The pentose compounds make up a large por- 
tion of the nitrogen- 



free extract. Straw 
is a food poor in pro- 
tein, fat and digestible 
carbohydrates, and 
contains a high per 
cent, of ligno-cellu- 
lose, pentose, and ash 
materials. Straw may 




-Composition of a bale of 
wheat straw. 



produce some heat in a ration, but for the production of 
muscle or the repair of proteid matter, it occupies about 



264 



AGRICULTURAL CHEMISTRY 



the lowest place in the list of animal foods. The various 
factors which influence the composition of plants (see 
Chapter XXVII) affect the composition of the straw. 
That from grain immaturely ripened has higher feeding 
value than from grain fully ripened, because in the unripe 
state less of the nutrients have been removed for seed 
formation. The greener the straw, the higher its food 
value. 

368. Timothy Hay. — Timothy hay has more protein, 
but in many respects the same general characteristics as 
straw. The per cent, of fiber usually ranges from 28 to 
32 per cent, or more, which is from 6 to 10 per cent, less 

than in straw. The 
amount of crude pro- 
tein ranges from 5.5 to 
9 per cent, according 
to the conditions under 
which the crop was 
grown. Average tim- 
othy hay contains 7.5 
per cent, which is 
about twice as much 
as found in straw. The amount of ether extract is about 
2.25 per cent., of which a large portion is non- fatty mate- 
rial. As in the case of straw, the nitrogen-free extract of 
timothy consists largely of pentose bodies ; there is also a 
small amount of soluble carbohydrates. While timothy 
hay is not rich in protein, it is a valuable fodder, particu- 
larly when one of fair energy-producing power is desired, 
as for feeding work horses. 




TIMOTHY HAY 



Fig. 85. — Composition of a bale of 
timothy hay. 



COMPOSITION OF COARSE FODDERS 265 

369. Hay, Similar to Timothy. — Millet, blue grass 
hay, and the numerous varieties of native prairie hay, have 
about the same general composition and feeding value as 
timothy hay. Each, however, differs from timothy to a 
slight extent both in chemical composition and structure 
of parts, some being preferable to others for feeding 
certain kinds of animals. These hays, particularly native 
prairie hays, vary in protein content from 6 to 1 1 per cent, 
according to the conditions under which they are grown 
and other factors which affect their composition. Tim- 
othy, blue grass and the numerous varieties of prairie 
hay, are classed as coarse fodders containing a low to 
a medium amount of crude protein. 

370. Oat Hay.— When oats are cut at the heading-out 
stage and cured as hay, they make a valuable fodder 
which compares favorably with the best grades of timothy 
hay, and usually contains slightly more protein than 
timothy or hays of similar character. Oat hay should be 
cured for fodder while the nutrients are evenly dis- 
tributed, and before they are transported and stored up 
in the grain. 

371. Hay, Similar to Oat Hay. — Wheat and other 
cereals, cut at the right stage, have a similar composi- 
tion and feeding value to oat hay. In localities where 
the climatic conditions do not admit of the growth of 
perennial grasses, these forage crops are grown in their 
stead. 

372. Bromus Inermis varies in composition and feed- 
ing value according to the stage when cut. When over- 



266 



AGRICULTURAL CHEMISTRY 



ripe, its protein content is between that of straw and 
timothy hay. If cut or pastured while young, it has a 
high feeding value. In this crop, the non-nitrogenous 
compounds, particularly fiber, are formed at a rapid rate 
in the last stages of growth. 

373. Clover Hay is characteristically rich in crude pro- 
tein, containing nearly twice as much as poor grades of 
timothy. It also contains less crude fiber and more ether 
extract. The large amount of crude protein and other 
nutrients makes it one of the most valuable fodders that 
can be produced for growing, fattening, or milk-giving ani- 
mals. There is no coarse fodder except alfalfa that has so 
high a protein content as clover when grown and cured un- 
der the best conditions. 



Clover ash is of differ- 
ent composition from 
that of timothy. It 
contains a small 
amount of silica and a 
clover hay large amount of lime, 

Fig. 86.— Composition of a bale of clover hay. while timothy ash 

contains a large amount of silica and a relatively small 
amount of lime. The nitrogen-free extract of clover is 
largely pentose materials. The composition and com- 
parative feeding value of early- and late-cut clover are 
given in Section 351. In curing clover hay, it should be 
the aim to prevent mechanical losses of leaves during the 
handling of the crop. When clover hay is fed to stock, 
less grain and milled products are required than when 
hays of lower crude protein content are used. There are a 




COMPOSITION OF COARSE FODDERS 267 

number of varieties of clover ; alsike, crimson, scarlet 
and white clovers, all having about the same general 
composition. Each, however, has characteristic habits of 
growth which makes it peculiarly adapted to certain soil 
and climatic conditions. 

374. Alfalfa and Fodders Similar to Clover. — Alfalfa 
has somewhat the same general composition and feeding 
value as clover, but its physical composition, as density 
of tissue and proportion of leaves to stems is different. 
It can be grown under different and more adverse climatic 
conditions. All members of the leguminous or pulse 
family, to which clover, alfalfa, peas, cow peas and vetch 
belong, are characteristically rich in protein, and are 
among the most valuable forage crops that can be pro- 
duced. The discovery, by Heilreigel, of the unique 
value of clover and other legumes in assimilating the free 
nitrogen of the air by means of the action of micro-organ- 
isms associated with the roots of these plants, and of the 
use of leguminous crops in increasing the supply of nitro- 
gen in the soil, is one of the greatest achievements of 
agricultural chemistry. In Plate III, the arrow indicates 
one of the nodules which contain the nitrogen-assimi- 
lating organisms. 

375. Rape. — The rape plant contains nearly as much 
crude protein as clover hay. Because of the presence of 
certain volatile oils, it cannot be fed to milk-cows with- 
out imparting an unpleasant taste to the milk. Rape, 
however, is valuable for the feeding of all growing and 
fattening animals. 



268 AGRICULTURAL CHEMISTRY 

376. Pasture Grass.— In the study of the composition 
of plants at different stages of growth, it was stated that 
the nitrogenous compounds are produced more rapidly 
than the non- nitrogenous (Section 351). The dry matter 
of pasture grass is more nitrogenous in character than 
that of the matured crop. The dry matter of all kinds 
of pasture grass is rich in crude protein ; the various 
nutrients, however, range between wide limits, accord- 
ing to the species of grass, and the conditions affecting 
its growth. When a piece of land is grazed, a smaller 
amount of total nutrients is secured than if a forage 
crop were harvested and fed. In pasturing, the results 
are similar to a series of early cuttings, before bloom, 
rather than one later cutting as in harvesting a crop. 

377. Corn Fodder and Stover. — By corn fodder is 
meant the entire corn plant with or without ears, accord- 
ing to the conditions under which it has been grown, 
while corn stover is the plant after the grain has been re- 
moved. Corn fodder is one of the most valuable, pala- 
table, and largest yielding crops that can be procured. 
When sown so that no ears, or very small ones, are de- 
veloped, the leaves and stalks contain all of the nutrients 
which would otherwise be stored up in the seed. When 
grown under favorable conditions, corn fodder contains 
about the same per cent, of crude protein and is equal in 
value to the best quality of timothy hay. When field- 
cured, it contains from 15 to 30 per cent, of water, from 
12 to 25 per cent, of crude fiber, and from 2.5 to 4 per 
cent, of ash. In the study of the composition of the corn 
plant (Chapter XXVI), the content of crude protein and 



COMPOSITION OF COARSE FODDERS 



269 




ETHER EXT 



other nutrients in the various parts of the plant was con- 
sidered. In the production of corn fodder, it should be the 
aim to produce a large number of me- 
diumly small plants with large leaves, 
small or no ears and small stalks. By 
so doing, the largest amounts of nutri- 
ents most evenly distributed, palata- 
ble, and digestible are secured. Corn 
stover has more of the characteristics 
of a straw crop, and is not as valuable 
as corn fodder. When ears are pro- 
duced, the protein is stored up in the 
grain, and hence less is found in 
stalks and leaves. The physical con- 
dition and chemical form of the cellu- 

Fig. 87.— Composition of 

lose, as hydrated or liguose, also in- a shock of corn fodder, 
fluence the feeding value of corn fodder and corn 
stover. Corn fodder can be fed to all kinds of farm 
animals, and is one of the cheapest forage crops that can 
be grown. It is valuable alike for horses, sheep, and 
dairy and beef cattle. 

378. Silage. — When silage is prepared, the green ma- 
terial is placed in a nearly air-tight compartment. Corn, 
clover, or any green crop may be cured as silage. Corn, 
however, is the crop most generally given this treatment 
and unless otherwise designated, silage usually has refer- 
ence to corn fodder prepared in this way. 

The chemical changes that take place in the silo are 
caused mainly by ferments. Carbon dioxid, hydrocar- 
bons, and ammonia in small amounts are among the vola- 



270 AGRICULTURAL CHEMISTRY 

tile products formed. There is always a loss of dry- 
matter in curing silage. This is greatest in the top layer 
and least in the bottom. The losses in the different 
sections of a large silo may range from 5 to 25 per 
cent. In a large silo the losses are less than in a small 
one, and they need not exceed 5 per cent, of the dry 
matter. 

The average of a number of trials shows that when 
corn fodder is prepared as silage, there is a loss of from 
5 to 25 per cent, of dry matter, of which a proportional 
amount is protein. Including mechanical losses, there is 
nearly the same loss in the field curing of corn fodder as 
in its preparation as silage. 

The temperature of the silage, when undergoing fer- 
mentation, ranges from 35 to 75 C. The lower tem- 
peratures generally produce poor silage, while the higher 
produce a better quality. In order to produce sweet 
silage, the conditions should be such that the temperature 
during fermentation is kept above 43 C, so as to render 
the acid spore that produces the sour silage less active and 
to allow other ferments to act. No appreciable amount of 
alcoholic fermentation takes place in the silo. In the 
production of silage, the corn should be cut in a green 
condition rather than when overripe, and evenly packed 
in the silo so that all parts will ferment alike. Compara- 
tively short fermentation at a high temperature is prefer- 
able to slow fermentation at a low temperature. 



COMPOSITION OF COARSE FODDERS 



271 



Averagk Composition of American Fodders. 
(Jenkins and Winton. ) 



Field-Cured Fodders. 



Corn fodder, average • • 

" minimum. 

" maximum 
leaves, average • • . 

" minimum. 

' ' maximum 
stalks, average . • • 

" minimum. 

" maximum 
stover, average . . . 

" minimum. 

" maximum 



Redtop 

Timothy: 

All analyses 

Cut in full bloom 

Cut soon after bloom 

Cut when nearly ripe 

Red clover 

Alsike clover 

White clover 

Alfalfa 

Cow pea 

Wheat straw 

Oat straw 

Green Fodders. 

Corn fodder (Flint) average • • • 
" " " minimum . 

" " " maximum. 



Pet. 
42.2 
22.9 
60.2 
30.0 
14.8 
44.0 
68.4 
5i-3 
78.5 
40.1 

15-4 

57-4 

8.9 

13.2 

i5-o 

14.2 

14.1 

15.3 

9-7 

9-7 

8.4 

10.7 

9.6 

9.2 



< 
Pet. 

2.7 

1-5 

5-5 
5-5 
4-3 
7-4 
1.2 
0.6 
2.0 
3-4 
i-7 
7.0 

5-2 



7 
7 
4 
5-i 



« 

Pet. 
4-5 
2.7 
6.8 
6.0 
4-5 
8-3 
1-9 
1.2 

3-0 
3-8 
1.8 

8-3 
7-9 

5-9 
6.0 

5-7 
5-o 

12.3 
12.8 
15-7 
14-3 
16.6 

3-4 
4.0 



Pet. 

14-3 
7-5 
24.7 
21.4 
17-4 
27.4 
11. o 
6.9 
16.8 
19.7 
14.1 
32.2 
28.6 

29.0 
29.6 
28.1 

3i.i 
24.8 

25.6 
24.1 
25.0 
20.1 
38.1 
37-o 



Pet. 

34-7 
20.6 
47-8 
35-7 
27-3 
44.1 
17.0 
11. 2 
26.0 
3i-9 
23-3 
53-3 
47-4 

45-o 
41.9 
44.6 

43-7 
38.1 
40.7 

39-3 
42.7 
42.2 

43-4 
42.4 



Pet. 
1.6 
0.6 

2-5 
1.4 
0.8 
2.2 
o-5 
o-3 
1.0 
1.1 
0.7 
2.2 
i-9 

25 
3-° 
3-o 
2.2 

3-3 
2.9 
2.9 
2.2 
2.9 
i-3 

2-3 



79.8 1.1 
5i-5 0.7 
90.8 1.8 



2.0 4.3 12. 1 0.7 
0.6 2.1. 4.3 0.3 
4.0 11. 4 36.3 1.3 



272 AGRICULTURAL CHEMISTRY 



« s 3? II fi« st; 

£ <j £S 55 ££ wS 

Green Fodders {continued). p c t. Pet. Pet. Pet. Pet. Pet. 

Corn fodder (Dent) average . •• 79.0 1.2 1.7 5.6 12.0 0.5 

" minimum . 59.5 0.6 0.5 2.0 3.0 0.1 

" maximum. 93.6 2.5 3.8 ir.o 27.0 1.6 

( Sweet varieti es ). •• 79.1 1.3 1.9 ••• 12.8 0.5 

(All varieties) 79.3 1.2 1.8 5.0 12.2 0.5 

in bloom 64.8 2.3 3.3 9.4 19. 1 1.2 

Timothy 61.6 2.1 3.1 11. 8 20.2 1.2 

Kentucky blue grass 65.1 2.8 4.1 9.1 17.6 1.3 

Legumes : 

Red clover 70.8 2.1 4.4 8.1 13.5 1.1 

Alfalfa 71.8 2.7 4.8 7.4 12.3 1.0 

Cowpea 83.6 1.7 2.4 4.8 7.1 0.4 

Sojabean 74.8 2.4 3.0 7.3 11. 5 1.0 

Silage : 

Corn 79.1 1.4 1.7 6.0 11. 1 0.8 



Redtop 



CHAPTER XXIX 
Wheat 
379. Structure of Kernel. — The wheat kernel has three 
distinct coverings (see Fig. 88): (1) The outer cuticle or 
pericarp which is a hard tough coat, composed largely of 
ligno-cellulose; this is the seed pod in which the seed is 
enclosed, and constitutes the main part of the bran. (2) 
An inner double cuticle of cellular tissue which is called 
the episperm and consists of two hard coats called respec- 
tively the inner and outer integument ; this double skin 
or layer may be considered one coat and forms a part of 




Fig. 88. — Structure of wheat kernel : i, Floury portion; 2, aleurone 

layer; 3, the bran composed of three layers; 4, germ 

(adapted from Bull. 32, Neb. Station). 

the bran. (3) A third, hard, thin skin or layer called the 
perisperm. The three bran coats constitute about 5 per 
cent, of the weight of the grain. Within these three 
bran layers is a single layer of large cells called the 
aleurone layer. This is sometimes erroneously called the 
18 



274 AGRICULTURAL CHEMISTRY 

gluten layer. The germ or embryo plant is present in 
the lower part of the kernel and opposite the rounded 
end. The germ constitutes about 6 per cent, of the 
weight of the kernel. The main part of the seed is the 
endosperm which is the floury portion, sometimes incor- 
rectly spoken of as the starch cells, in reality composed of 
starch, gluten, mineral matter, and other compounds in 
small amounts. Additional information in regard to the 
structure of the wheat kernel is given in Bulletin No, 32 
of the Nebraska Experiment Station. 

380. Proteids of Wheat. — Wheat contains the largest 
amount of proteids of any of the cereals, and also proteids 
of an entirely different character. There are five sepa- 
rate proteids in wheat : (1) An albumin (leucosin), (2) 
a globulin (edestin), (3) a proteose, and two insoluble 
proteids called (4) gliadin, and (5) glutenin, which to- 
gether constitute the gluten. Wheat gluten can be ob- 
tained by washing a sample of dough from wheat meal or 
flour with water to remove the starch and other non -glu- 
ten compounds. The gluten mass from hard wheat is 
usually elastic and tenacious, varying in quality according 
to the nature of the wheat from which it was obtained. 
The milling qualities of wheat, and the baking qualities 
of flour are determined largely by the composition of the 
gluten. 

Wheat gluten is composed of two proteids, gliadin and 
glutenin ; these form about 85 per cent, of the proteids 
of wheat. The gliadin may be extracted from either 
gluten or flour with a 70 per cent, solution of alcohol, 
and is obtained, after evaporating the alcohol, in the form 



WHEAT 275 

of thin, transparent flakes which resemble gelatin. In 
fact, gliadin was called by the earlier investigators, plant 
gelatin. When moistened, the gliadin expands and forms 
a mucilagenous mass. When more water is added, a 
small amount is dissolved. Gliadin is soluble in dilute 
acid and alkali solutions ; in many wheats, particularly 
those which have undergone slight fermentation, there is 
sufficient acid developed to combine with and render solu- 
ble appreciable amounts. Gliadin, like all of the wheat 
proteids, is characterized by a high per cent, of nitrogen. 
Gliadin takes a very important part in bread-making, and 
is the material which binds together the flour to form 
dough and enables the mass to expand, retaining the gas 
generated by the yeast. Wheat gluten contains from 60 
to 70 per cent, of gliadin and from 30 to 40 per cent, of 
glutenin. 

Glutenin is the proteid which remains after extracting 
the gliadin from the gluten. When dry and pure, it 
forms a light gray mass which may be reduced to a fine 
powder. Glutenin is insoluble in dilute alcohol and salt 
solutions and is only sparingly soluble in water, but is 
readily soluble in dilute acid and alkali solutions. This 
proteid also takes an.important part in bread-making. It 
combines mechanically with the gliadin and, "serving as 
a nucleus to which the gliadin adheres," prevents the 
dough from becoming too soft and sticky. When these 
two proteids are present in the proportion of about 65 per 
cent, of gliadin to 35 per cent, of glutenin, a much better 
quality of bread can be produced than from flour contain- 
ing the same amount of total proteids but of which 75 per 



276 AGRICULTURAL CHEMISTRY 

cent, is gliadin and 25 per cent, glutenin. Two samples 
of wheat may contain the same amount of gluten, and 
the flour from one produce good bread, while that from 
the other is of very poor quality. The most valuable 
wheats for bread-making purposes are those in which 80 
to 85 per cent, of the protein is gluten, and the gluten is 
composed of from 60 to 65 per cent, gliadin and 35 to 40 
per cent, glutenin. A wheat may produce a good quality 
of bread and at the same time contain a low per cent, of 
protein, while, on the other hand, poor bread-making 
qualities can be associated with a high per cent, of pro- 
tein. Glutens which are usually considered the most 
valuable for bread-making purposes are hard, elastic, and 
of a light yellowish tinge. Poor gluten is dark in color, 
has an uneven surface, possesses but little power to re- 
coil, and is very sticky. 

Experiment 69. — Gluten from wheat flour. To about 30 grams 
of flour made from hard spring wheat, add sufficient water to form 
a stiff dough and allow it to stand for half an hour, in order that 
the physical properties of the gluten may develop. Place the dough 
in a cloth and work it gently with the fingers, while a stream of 
water is allowed to flow over it. Continue the washing until 
the water that runs away is clear, which indicates that all starch 
has been washed out of the dough. The washing may be completed 
with the mass in the hand. Leave this gluten in water until 
the gluten from flour made from soft winter wheat has been pre- 
pared. Compare the two samples of gluten. 

Questions. (1) What is wheat gluten? (2) Describe hard 
wheat gluten. (3) How does it differ from soft wheat gluten? 
(4) How do the two moist glutens compare as to weight? (5) 
Which gluten contains the larger amount of gliadin ? (6) Which 
is the better quality of gluten for bread-making purposes? 



WHEAT 277 

Experiment 70. — Gliadin from flour. Place in a flask 10 grams 
of flour, 30 cc. of alcohol, and 20 cc. of water. Cork the flask and 
shake, and after a few minutes shake again. Allow the alcohol to 
act on the flour for an hour or until the next day. Then filter off 
the alcohol solution and evaporate the filtrate to dryness over the 
water-bath. Examine the residue. To a portion add a little water. 
Burn a little. Treat a little in a test-tube with water containing a 
few drops of HC1. 

Questions. (1) Describe the appearance of the gliadin. (2) 
What was the result when water was added? (3) When burned, 
what was the odor of the gliadin, and what does this indicate ? (4) 
What effect did the dilute HC1 have upon the gliadin? (5) What 
is gliadin ? 

Composition of Wheat Gluten 

^ a Per cent, of 

t^ rt _• s gluten in 

c ^ .Be -5 '3 form of 

'3 x >3 v "5 <y , '■ , 

o^- ;S-g .2 3 Glia- Glute- 
^6. Cm O O din. n i n - 

1. Scotch fife 14.76 12.46 7.26 5.20 58.3 41.7 

2. Wellman's fife 12.60 10.18 6.14 4.04 60.3 39.7 

3. Red winter wheat 10.73 8.68 5.60 3.08 64.5 35.5 

4. Early Genesee winter 7.98 6.31 3.71 2.60 58.8 41.2 

5. Ladoga 9.54 8.25 5.64 2.61 68.5 31.5 

6. Blue stem 14.20 11.75 7-§4 3-9 1 66.7 33.3 

7. Crimean 11.08 9.49 5.77 3.72 60.8 39.2 

8. Frosted spring wheat 12.88 6.39 4.25 2.14 66.5 33.5 

9. Calcutta (India) 8.13 6.70 4.90 1.80 73.1 26.9 

10. No. 1 Chili 7.01 5.62 2.92 2.70 52.0 48.0 

11. La Plata (Argentine Rep. ) 13.38 11.84 4-99 6.85 42.1 57.9 

12. Nicolaeff Azima (Russia). 10.28 8.74 5.70 3.04 65.2 34.8 

13. Oregon white winter 9.23 7.65 5.42 2.23 70.8 29.2 

14. No. 2 red winter wheat. . . 7.01 5.56 3.77 1.79 67.8 32.2 

15. No. 2 hard winter wheat. 8.83 7.31 3.99 3.32 54.6 45.4 

381. Relation of Nitrogen in Wheat to Nitrogen Con- 
tent of Flour. — Medium- sized, well-formed wheat kernels 



278 . AGRICULTURAL CHEMISTRY 

usually contain more nitrogen and gluten than large, 
rotund kernels. The size of the germ, the proportion of 
aleurone to endosperm, and the nitrogen content of the 
endosperm or floury portion are the three factors which 
determine the relation of the nitrogen in the wheat to the 
nitrogen in the flour. Ordinarily, the germ makes up 
about 7 per cent, of the weight of the kernel, and the 
endosperm from 82 to 86 per cent. When the amount of 
endosperm is increased, there is proportionally less germ, 
and aleurone, and a larger amount of flour is secured. 
The size of the wheat kernel together with the size of the 
indentation marking the germ area indicate approxi- 
mately the amount of germ in the kernel. The larger 
the amount of germ and aleurone, the smaller the amount 
of flour recovered when the wheat is milled. As a general 
rule, wheats which contain the largest amount of nitro- 
gen produce the most nitrogenous flours, but the total 
nitrogen in the wheat cannot always be taken as an index 
of that in the flour. Two wheats frequently contain 
about the same total nitrogen but the nitrogen is distrib- 
uted differently in each; in one a larger portion is present in 
the germ and aleurone, and in the other a larger amount 
is in the endosperm and hence recovered as flour. In the 
following table, the per cent, of protein in the grain and 
that in the patent flour recovered by the modern roller 
process of milling are given. These tests were made 
under the supervision of the author in two of the large 
flour mills of Minneapolis, Minn. The percentage 
amounts of wheat recovered as patent flour were about 
the same in all of the tests. 



WHEAT 



279 



Per Cent, of Protein. 


Wheat. 

15-19 


Mill B 


Flour. 
14.60 


15-44 




14-13 


15-75 


Mill C 


14.OO 


15-50 

15.38 

14-33 
I5-5I 




13.90 
14.65 
13.88 

14-44 


15.00 
15-15 




13-94 
14.06 


15-33 
15.00 




12.50 
12.56 


15-19 




14.19 



382. Influence of Fertilizers upon Composition of 
Wheat. — Experiments by Lawes and Gilbert (Rotham- 
sted Memoirs, Vol. Ill) show that the different kinds of 
manure, as nitrogenous, mixed and mineral, influence 
the yield but not materially the composition of the grain. 
During the time of the experiment, covering a period of 
twenty years, the nitrogen, phosphoric acid, and potash 
in the dry matter of the grain were fairly constant, and 
when different manures were used, there were no greater 
variations in the composition of the grain than were 
observed between crops upon the same plots similarly 
manured during different seasons. Climatic conditions 
influenced the composition of the kernel to a greater 
extent than did fertilizers. 

383. Variations in Composition of Wheat. — In Jen- 
kins' and Winton's "Average Composition of American 
Feeding Stuffs," spring wheat is given as containing 12.5 



28o AGRICULTURAL CHEMISTRY 

per cent, protein and winter wheat 1 1.8 per cent. In 
both spring and winter wheat, variations in protein from 
8 to 16 per cent, are noticeable. While average wheat 
contains 12.5 per cent., some samples contain as low as 8 
and others as high as 18 per cent. 

The greatest differences in composition are noticeable 
when wheat grown at different seasons is compared. 
Five samples of the 1891 crop of wheat analyzed by the 
Minnesota Experiment Station contained 12.01 percent, 
of protein. The wheat was of unusually high milling 
and baking value. In 1892, six samples from the same 
localities showed 13.22 per cent, of protein, and in 1901, 
14 samples contained 15.21 per cent. 

Some of the effects of climate and soil upon the phys- 
ical and chemical properties of wheat are noted in Bulletin 
No. 1 8, Part 9, Division of Chemistry, U. S. Department 
of Agriculture, from which the following paragraphs are 
taken : 

" The inherent tendency to change which is found in 
all grains is most prominent in wheat ; it may be fostered 
by selection and by modifying such of the conditions of 
environment as it is in the power of man to effect. The 
most powerful element to contend with is the character 
of the season or unfavorable climatic conditions. The 
injury done in this way is well illustrated in Colorado, 
and it would seem advisable in such cases to seek seed 
from a source where everything has been favorable, and 
begin selection again. It must be borne in mind that 
selection must be kept up continuously, and that rever- 
sion takes place more easily than improvement. It took 



WHEAT 28l 

but one season to seriously injure Professor Blount's 
wheats, but it will be two or more years before they have 
recovered from that injury. Hallett, in England, was 
able to make his celebrated pedigree wheat by selection, 
carried on through many years, but the same wheat 
grown by the ordinary farmer under unfavorable con- 
ditions for a few years without care has reverted to an 
ordinary sort of grain. 

' ' The effect of climate is well illustrated by four speci- 
mens of wheat which are to be seen in the collection of 
the Chemical Division. Two of these were from Oregon 
and Dakota some years ago, and present the most ex- 
treme contrast which can be found in this variable grain. 
One is light yellow, plump and starchy, and shows on 
analysis a very small per cent, of albuminoids ; the other 
is one of the small, hard, and dark-colored spring wheats 
of Dakota, which are rich in albuminoids. Between these 
stand two specimens from Colorado, which have been 
raised from seed similar to the Oregon and Dakota wheat. 
They are scarcely distinguishable except by a slight dif- 
ference in color. The Colorado climate is such as to have 
modified these two seed wheats, until after a few years 
growth they are hardly distinguishable in the kernel. 
All localities having widely different climates, soils, or 
other conditions produce their peculiar varieties and 
modify those brought to them. The result of these ten- 
dencies to change and reversion from lack of care in seed 
selection or other cause has led to the practice of change 
of seed among farmers. A source is sought where either 
through greater care or more favorable conditions the 



282 AGRICULTURAL CHEMISTRY 

desired variety has been able to hold its own. Some- 
times this change is rendered necessary by conditions 
which are beyond the power of man to modify. As an 
example, No. 10 of Professor Blount's wheats, known as 
" Oregon Club," a white variety from Oregon, has been 
deteriorating every year since it has been grown in Colo- 
rado, whereas if the seed had been supplied every season 
directly from Oregon, the quality would probably have 
remained the same. In extension of this illustration the 
fact may be mentioned that the annual renewal of the 
seed from a desirable and favorable source often makes it 
possible to raise cereals where otherwise climatic con- 
ditions would render their cultivation impossible through 
rapid reversion. This is particularly the case with 
extremes in latitude, the effect of which is not founded 
so much upon the composition of the crop as on the yield 
and size of the grain." 

384. Storage of Wheat in Elevators. — When new 
wheat is stored in elevators, a fermentation change takes 
place known as ' ' sweating. ' ' This affects, to a slight 
extent, the chemical composition and milling qualities of 
the grain. When wheat is not fully matured or is damp, 
the fermentation which takes place causes the tempera- 
ture to rise to 140 or more and occasionally high enough 
to cause spontaneous combustion. Thoroughly sound 
wheat undergoes but little change in temperature even 
when stored in large elevators where 120,000 bushels are 
placed in one compartment. The changes which take 
place during storage are brought about by the enzymes 
or soluble ferments in the grain, and the organized fer- 



WHEAT 283 

merits and moulds that are present on the surface of the 
grain. When wheat has been thoroughly cleaned, it 
does not readily undergo fermentation, while uncleaned, 
damp and unsound wheats deteriorate. 

385. Grading of Wheat. — Wheat is graded entirely 
upon the basis of its physical properties, as : Weight per 
bushel, size and appearance of the kernels, freedom from 
foreign seeds, soundness of the kernel and absence of 
blemishes caused by frost, bleaching, sun scalding or 
sprouting. The spring and winter wheat grades estab- 
lished for the 1902 crop by the Minnesota Railroad and 
Warehouse Commission, are as follows : 

No. 1 hard spring wheat must be sound, bright and well cleaned, 
and must be composed mostly of hard Scotch fife, and weigh not less 
than 58 pounds to the measured bushel. 

No. 1 northern spring wheat must be sound and well cleaned, and 
must be composed equally of the hard and soft varieties of spring 
wheat, and weigh not less than 57 pounds to the measured bushel. 

No. 2 northern spring wheat must be sound and reasonably clean, 
this grade to include all wheat not suitable for the higher grades 
on account of smut, barley, or too much king heads, cockle and 
oats, or any other defects, and to weigh not less than 56 pounds to 
the measured bushel. 

No. 3 spring wheat shall comprise all inferior shrunken spring 
wheat weighing not less than 54 pounds to the measured bushel. 

Note. Hard, flinty wheat, of good color, containing no appreci- 
able admixture of soft wheat, may be admitted into the grade of 
No. 2 northern spring and No. 3 spring wheat, provided the test 
weight of the same is not more than one pound less than the mini- 
mum test weight required by the existing rules for said grades, and 
provided further that such wheat is in all other respects qualified 
for admission into such grades. 



284 AGRICULTURAL CHEMISTRY 

Rejected spring wheat shall include all spring wheat grown badly 
bleached, or for any other cause unfit for No. 3 wheat. 

Note. Wheat containing admixture of "rice" or "goose" wheat 
will in no case grade better than rejected. 

" No grade" wheat. All spring wheat that is in a heating condi- 
tion, too musty or too damp to be safe for warehousing, or that is 
badly bin-burnt, badly damaged, exceedingly dirty, or otherwise 
unfit for storage shall be classed as "no grade' ' with inspector's nota- 
tion as to quality and condition. 

Note. The amount of dirt in all wheat shall be determined by 
the inspectors. 

No. 1 white winter shall be sound, well cleaned, reasonably 
plump, and composed of the white varieties. 

No. 1 winter to be sound, well cleaned, reasonably plump, and 
composed of the mixed white and red winter. 

No. 2 winter to be sound, reasonably clean, and composed of the 
mixed white and red winter. 

No. 3 winter shall comprise all winter wheat fit for warehousing, 
weighing not less than 54 pounds to the measured bushel, not sound 
enough or otherwise unfit for No. 2 of the other grades. 

Rejected winter, fit for warehousing but otherwise unfit for No. 3. 

386. Composition of Unsound Wheat. — When wheat 
fails to full} r mature or is affected by frost, fungus dis- 
ease, as rust or smut, or excessive heat causing bleach- 
ing, the composition of the kernel is affected. Such 
wheats usually contain a larger percentage of soluble car- 
bohydrates, organic acids, and soluble proteids than fully 
matured wheat. Generally, the percentage amount of 
protein is higher although sometimes it is lower than in 
normal wheat. Wheat which has been damaged by 
bleaching, frost or fungus disease gives a lower yield of 
flour with poorer keeping and bread-making qualities. 



WHEAT 285 

Sound wheat of high milling qualities usually contains 
not more than 0.25 per cent, of acid bodies, less than 2 
per cent, of soluble carbohydrates, and 1 per cent, sol- 
uble proteids. 

387. Composition of Different Varieties of Wheat 

The different varieties of wheat, as spelt and durum, are 
similar in composition to ordinary wheat with minor vari- 
ations in protein and fiber content. Spelt has a chaffy 
covering which gives it somewhat the same proximate 
composition as barley, but when the chaff is removed 
the seed has about the same general composition as 
wheat. In durum, the percentage of protein varies with 
the conditions under which the grain is grown. In the 
table given at the close of this chapter, it will be seen 
that durum has about the same content of proteid matter 
and other nutrients as hard spring wheat grown under 
similar conditions. 

Experiment 71. — Grading wheat. Make the following tests with 
three samples of wheat. (1) Obtain the weight per quart (dry- 
measure), and then calculate the weight per bushel of each. (2) 
Weigh 100 kernels of each sample. (3) Place ten representative 
kernels (of each) end to end and measure the length in millimeters 
and inches. (4) Note the color and appearance of each sample. 
(5) Observe if the kernels are "well filled;" (6) free from weed 
seeds and if there are any indications of smut, frosting, or bleach- 
i n g- (7) Assign a grade to each sample (see Section 385). 

388. American and Foreign Wheats. — A compilation 
of analyses of wheats and other cereals grown in different 
countries has been made by Konig. Absolute compari- 
sons as to composition cannot be made because of numer- 
ous local factors which affect the wheat, as climate and 



286 AGRICULTURAL CHEMISTRY 

soil. As great a difference is found in the composition 
of wheats raised in various parts of the United States, as 
between wheats of different countries where there exist 
similar varieties of climate and soil. In the case of 
American wheats, the tables given were compiled before 
any large number of Northwestern wheats were analyzed, 
hence the protein content is low because so small a number 
of wheats of highest protein content are included in the 
averages. In general, the tables of analyses show that 
wheat grown in tropical climates is less nitrogenous than 
that grown in more northern latitudes on equally fertile 
soils. In making use of the figures given in the follow- 
ing tables, it should be remembered that the comparisons 
are only relative as some of the samples contain a much 
larger amount of moisture than others, and an equal num- 
ber, or samples proportional to the wheat-growing regions, 
are not included in the averages. 

389. Wheat as Animal Food. — Wheat is not generally 
used for fattening farm animals because of its high value 
as human food. Occasionally, however, it is more 
economical to use it in preference to other grains for the 
feeding of stock. Experiments have shown that it has a 
high feeding value. As a food for growing pigs, it is 
somewhat preferable to corn ; for fattening pigs, there is 
but little difference between wheat and corn. The best 
results, however, are obtained when wheat is ground and 
fed with other grains. A mixture of equal parts of 
ground wheat and corn gives better results than when 
either wheat or corn is fed alone. When the price of 
wheat is low and it can be purchased for the same 



WHEAT 287 

or less per pound than corn, it will pay to use wheat for 
feeding farm animals. As a food for dairy animals, 
ground wheat is fully equal to either corn or a mixture 
of corn and barley, and when fed to fattening steers, 
ground wheat produces about the same results as ground 
corn. 

390. Wheat as Human Food. — Wheat is used as human 
food more extensively than any other cereal. This is 
due largely to its being produced over wider ranges of 
latitude and its containing proteids specially adapted to 
bread-making. With the exception of rye, wheat is the 
only grain which contains gliadin, the proteid which 
forms the dough and with the gas causes expan- 
sion of the mass during the process of bread-making. 

Composition of Wheat 

(Mainly from Jenkins & Winton, Bull. II, U. S. Dept. Agr., Office 
of Expt. Sta. ) 



££ 2.8 



K" L L -4-1 ..-1 <U J-..Q tfi 

Pet. Pet. Pet. Pet. Pet. Pet. 

Wheat, spring 10.4 12.5 2.2 71.2 1.8 1.9 

Wheat, spring (max. ) 13.4 15.4 2.6 78.7 2.3 2.6 

Wheat, spring (min.) 8.1 8.1 1.8 66.1 1.3 1.5 

Wheat, winter 10.5 11. 8 2.1 72.0 1.8 1.8 

-f- Wheat, spelt 1 10. o 11.3 2.3 63.9 9.2 3.3 

-f- Wheat, durum 2 10.7 15.0 2.4 ( 69.9 ) 2.0 

+ Wheat, No. 163 s 11. 2 15.8 2.3 ( 68.8 ) 1.9 

1 Minn, analyses. 

2 Average of thirteen northern grown samples. 

3 Spring wheat grown under similar conditions as durum. 



288 



AGRICULTURAL CHEMISTRY 



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CHAPTER XXX 
Maize (Indian corn) 

391. Structure of the Kernel. — Corn has somewhat 
the same general structure as wheat. The seed coat, how- 
ever, is composed of two instead of three layers (see Fig. 
89). Within the seed coat or hull (1) there is a hard 
aleurone layer (2) which 
is thicker at the sides 
than at the crown. The 
floury portion (4) which 
is usually hard and flinty, 
makes up the larger 
part of the kernel while 
the germ (3) constitutes 
about 10 per cent, of the 
weight. The propor- 
tional amounts of germ, 
floury portion, and aleu- 
rone layer, differ with 
individual samples. The 
hulls make up about 5.5 
to 6 per cent, of the 
kernel, while about 85 
per cent, is present in 
the floury portion and aleurone layer. In the milling of 
corn, as in the milling of wheat, a mechanical separation 
of the different parts is effected. 

392. Composition of Corn. — Corn is fairly constant in 




Fig. S9.— Structure of corn kernel: I, 
Seed coat; 2, aleurone layer; 3, germ; 
4, floury portion (adapted from N. J. Expt. 
Station Bull.). 



290 AGRICULTURAL CHEMISTRY 

composition. As the result of a large number of analyses 
made by the Department of Agriculture, the following 
conclusion is drawn : "A study of all the analyses which 
have been made reveals the fact that maize is one of the 
most unvariable of the cereals, maintaining under the 
most different climatic conditions, a most remarkable uni- 
formity of composition, varying chiefly in the size, color, 
and general physical characteristics of its kernels rather 
than in their composition." 

From the figures given at the close of the next chapter 
it will be observed that corn contains a much larger 
amount of fat than wheat, also a somewhat smaller 
amount of protein ; the nitrogen-free extract, which is 
mainly starch, is about the same in amount in both. In- 
vestigations at the Illinois Experiment Station show that 
all of the kernels upon the same ear are fairly constant 
in composition, although the kernels on the tip of the ear 
have a tendency to contain slightly less protein than those 
either in the middle or at the base; the differences in both 
protein and carbohydrates in a few extreme cases was about 
1 per cent. The composition of the kernel is slightly in- 
fluenced also by the stage of maturity. If, for any rea- 
son, corn fails to reach full maturity, there is usually a 
somewhat larger amount of protein and smaller amount 
of carbohydrates in the dry matter. 

393. Proteids of Corn. — The proteids of corn are quite 
different in character from those of wheat. Small 
amounts of albumin and globulin are present but the 
larger portion of the corn proteids is in insoluble forms 
called zeins, one of which is soluble and the other insol- 



MAIZE 



29I 



uble in alcohol. The zeins differ in both physical and 
chemical composition from wheat gliadin. The corn 
proteids contain about 1 part nitrogen to every 6.23 
parts proteid material, while in wheat there is about 1 
part nitrogen to 5.7 of proteids. 

394. Nitrogenous and Non=Nitrogenous Corn. — The 
germ and aleurone layers are more nitrogenous in char- 
acter than the interior or floury portion of the kernel. 
Since the proportion of germ and aleurone in corn, as in 
wheat, varies with individual samples, the nitrogenous 
matter, being greater in these parts, also varies. Taking 
advantage of this knowl- 
edge, it is possible, by 
mechanical means, to 
distinguish corn samples 
of high from those of low 
protein content. Hop- 
kins, of the Illinois 
Experiment Station, was 
the first to direct atten- 
tion to this fact (Bulle- 
tin 55, Illinois Expt. 
Station). 

' ' By making cross sec- 
tions and longitudinal 
sections of several kernels 
from an ear of corn, one 
can judge, with a very 
satisfactory degree of ac- 
curacy, whether the corn is rich or poor in protein. The 




Fig. go. — Nitrogenous and non-nitroge- 
nous corn: I, Corn with 14.92 per cent, pro- 
tein; 2, corn with 7.76 per cent, protein. 



292 AGRICULTURAL CHEMISTRY 

illustration (Fig. 90) here shown was made from a photo- 
graph taken of the corn kernels and sections with a mag- 
nification of three diameters. At the left are two sections 
and a whole kernel from corn containing 14.92 per cent, of 
protein. The sections and kernel at the right are from corn 
containing 7.76 per cent, of protein. About one-fourth 
of the kernel was cut off from the tip end in making the 
cross sections. In the longitudinal sections the tip end 
of the kernel points upward to the right. It will be 
seen that in the cross sections the white starchy layer 
nearly disappears in the high-protein corn, but becomes 
very prominent in the low-protein corn. In the longi- 
tudinal sections this difference is also apparent, the white 
starch in the high-protein corn being confined almost en- 
tirely to the crown end of the kernel, while in the low- 
protein corn it extends into the tip end in considerable 
amount. The germ in the high-protein corn is somewhat 
larger. This is also indicated by the depressions in the 
whole kernels." 

Exceptions are, however, occasionally observed in the 
relation of the form to the protein content of corn, but 
in making comparisons in the manner indicated, the few 
errors which are liable to occur are in assigning too low 
rather than too high a protein value to the sample. In 
the selection of seed corn a knowledge of the character- 
istic of the kernels as nitrogenous or non-nitrogenous will 
be found of value. 

Experiment 72. — Select, from a sample of corn, kernels of highl- 
and kernels of low-protein content. Make longitudinal and cross 
sections of some of the kernels, and note the proportion of germ, 



MAIZE 293 

aleurone, and floury parts in each. Make a drawing of a repre- 
sentative kernel of each kind of corn. Observe how your rating of 
the corn compares with the chemical analysis. Determine the 
weight per bushel and assign a grade to the sample. 

395. Varieties of Corn. — The numerous analyses, which 
have been made of the different varieties of corn as dent 
or flint, do not show any wide variations in composition 
when they are grown under similar conditions. The 
main differences are in the amount of coloring-matter and 
in the physical characteristics rather than in chemical 
composition. Yellow corn contains no more nutrients 
than white corn ; there is coloring-matter present in one 
and not in the other. Sweet corn contains more sucrose 
than other varieties but otherwise it has about the same 
general composition as the dent and flint varieties. 

396. Grading of Corn. — Corn is graded entirely upon 
the basis of its physical properties and soundness rather 
than on the basis of chemical composition. The rules 
governing the grading of corn adopted by the Minnesota 
Railroad and Warehouse Commission in 1902 are as 
follows : 

No. 1 yellow corn shall be sound, yellow, dry, plump, and well 
cleaned. 

No. 2 yellow corn shall be three-fourths yellow, dry, reasonably 
clean, but not plump enough for No. 1. 

No. 3 yellow corn shall be three-fourths yellow, reasonably dry, 
reasonably clean, but not sufficiently sound for No. 2. 

No. 1 white corn shall be sound, dry, plump, and well cleaned. 

No. 2 white corn shall be seven-eighths white, dry and reason- 
ably clean, but not plump enough for No. 1. 



294 AGRICULTURAL CHEMISTRY 

No. 3 white corn shall be seven-eighths white, reasonably dry and 
reasonably clean, but not sufficiently sound for No. 2. 

No. 1 corn shall be mixed corn of choice quality, sound, dry, and 
well cleaned. 

No. 2 corn shall be mixed corn, dry, reasonably clean, but not 
good enough for No. 1. 

No. 3 corn shall be mixed corn, reasonably dry and reasonably 
clean, but not sufficiently sound for No. 2. 

No. 4 corn shall include all corn not wet and not in heating con- 
dition that is unfit to grade No. 3. 

No grade corn : All corn that is in a heating condition, too 
musty or too damp to be safe for warehousing, or that is badly 
damaged, exceedingly dirty, shall be classed as no grade. 

(These rules are subject to change from year to year.) 

397. Corn Products When the entire kernel is 

ground, coarse cornmeal is the product. When a part 
of the corn bran is removed, fine cornmeal is obtained. 
When the bran and germ are removed and the interior 
portion of the kernel is reduced as in flour-making, the 
product is corn flour. By mechanical means, as in the 
manufacture of starch, the proteid matter can be re- 
moved. Cornstarch is sold either as a commercial prod- 
uct, or is used in the preparation of glucose (see Experi- 
ment 49). The germ, bran and glutinous matter are by- 
products which form the basis of a number of commercial 
feeds. The larger portion of the fat or oil of corn is 
present in the germ and is recovered as corn oil. A num- 
ber of other products are also obtained from corn. 

398. Corn as a Food. — Corn is extensively used both 
as human and animal food. Its proteids, however, do 
not render it as valuable for bread-making purposes as 



MAIZE 295 

wheat, and on this account, in some countries, it is not as 
generally used for human food. It is, however, one of 
the cheapest foods that can be procured, and the preju- 
dice against its use as human food because of its being 
fed to animals is gradually being overcome. Its value 
as animal food is too well known to require further dis- 
cussion. 



CHAPTER XXXI 

Oats, Barley, Rye, Buckwheat, Rice, and MisceU 

laneous Seeds 

399. Structure of the Oat Kernel.— Oats are composed 
of two parts, the kernel and the hull. The hulls have 
the same general composition as straw, and make up 
about 30 per cent, of the weight. The different parts of 
the oat kernal are : (1) Seed pod, (2) aleurone layer, (3) 
germ, and (4) floury portion. The weight per bushel of 
oats depends largely upon the amount of hulls ; in some 
samples these make up 25 per cent., and in others 35 per 
cent, of the weight. 

400. Composition of Oats.— When the hulls are in- 
cluded, oats have a larger amount of fiber and ash than 
any other cereal. The per cent, of fat is higher than in 
wheat, barley or rye, and as high as in corn. Hulled 
oats have about the same general composition as wheat, 
with a tendency to a higher protein content. They are 
also characterized by a high per cent, of fat. Variations 
in the composition of oats are, to a limited extent, 
noticeable. The ratio of hull to kernel influences the 
composition more than any other factor. There is not a 
great difference in the chemical composition of heavy- and 
light-weight oats. Experiments at the Maine Experi- 
ment Station show that the differences are mainly in the 
amount of nutrients in a given volume of the grain, as a 
bushel, rather than in percentage composition. This em- 



OATS, BARLEY, RYE, ETC. 297 

phasizes the importance of feeding oats by weight rather 
than by measure. 

401. Oats as Human and Animal Food. — Oats are used 
more extensively as an animal food than as human food. 
When the hulls are removed and the oats are prepared 
as human food, they have a high value because of 
the large amount of available protein, fat and other 
nutrients which they contain. As an animal food oats 
are especially well adapted for the feeding of horses, be- 
cause of their mechanical condition and the com- 
paratively large amount of available nutrients. Ex- 
periments at the Wisconsin Experiment Station show 
that when fed to dairy animals under similar conditions, 
oats produce 10 per cent, more milk and butter fat than 
the same weight of bran. 

402. Barley is used largely for brewing and for animal- 
feeding purposes rather than as a human food. There is 
less fat, fiber, and ash than in oats, but more protein and 
carbohydrates. Barley contains less protein than wheat. 
For brewing purposes, perfectly sound and fully matured 
barley is necessary, while that which has been slightly 
damaged in any way, as by rain, frost or hot winds, is not 
suitable for this purpose. Such barley, however, can be 
used for feeding purposes and is frequently the cheapest 
grain that can be fed by western farmers. Barley is 
suitable for the feeding of all kinds of farm animals. The 
hulless varieties contain less fiber and more protein and 
available carbohydrates. A study of the proteids of bar- 
ley shows that there is about i part of nitrogen to 



298 AGRICULTURAL CHEMISTRY 

every 5.7 parts of protein, which is about the same in 
amount as is found in wheat proteids. 

403. Rye. — Rye contains proteids similar to wheat, 
rendering it suitable for bread-making purposes. How- 
ever, rye is more extensively used in this country for the 
manufacture of alcoholic beverages than for bread. Rye 
resembles wheat in chemical composition more than any 
other cereal, although when grown under similar condi- 
tions it contains somewhat less protein than wheat. In 
the feeding of farm animals, rye must be used with more 
caution than wheat. If used in a dairy ration in too 
large amounts, it is believed to have a tendency to pro- 
duce a slightly inferior quality of milk and butter, but 
when fed in small amounts no difficulty is experienced. 
In a mixed ration, rye has been found equal to barley and 
other cereals for meat production. 

404. Rice — Rice is characterized by a low-protein and 
fat content, and a high per cent of carbohydrates. It is 
not used to any extent for the feeding of stock, although 
a number of its by-products are employed for this pur- 
pose. 

405. Buckwheat. — The entire kernel contains quite 
an appreciable amount of fiber, which is removed in the 
preparation of buckwheat flour. The amount of protein 
is somewhat less than in wheat and other cereals. 
Buckwheat is not extensively used for the feeding of ani- 
mals, although some of its by-products are valuable for 
this purpose. 

406. Flax is a type of oil seed, small in size but with a 



OATS, BARLEY, RYE, ETC. 299 

large amount of nutrients in the form of fat. Average 
flax contains about 38 per cent, of fat which is largely- 
removed in the manufacture of linseed oil. A bushel of 
flax will yield about 19 pounds of oil and 40 pounds of 
oil cake. Flax is too concentrated and usually too valu- 
able a market crop to be used for animal-feeding pur- 
poses. Should the price warrant, it can be used, but it 
should be combined with other grains, although 8 pounds 
a day have been fed in a dairy ration without apparent ill 
results. Unripe and immature flaxseed are often used for 
feeding purposes. Other oil seeds, as cotton seed and 
rape, are valuable for the oil which they contain, and the 
oil cake which is used for feeding purposes. 

407. flillet Seed has somewhat the same general com- 
position as oats. When fed, however, it should be ground 
and combined with other grains. 

408. Peas and Beans. — Peas and beans, as well as other 
leguminous seeds, are characterized by containing large 
amounts of protein and variable amounts of fat. Peas 
and beans are alike valuable as human and animal food. 
When used as animal food, they should form a part 
of a grain ration. They are particularly valuable for 
pork production as well as for meat and milk, but their 
high price usually prevents their extensive use in ani- 
mal-feeding. When they can be produced cheaply and 
abundantly, they are among the most valuable foods that 
can be used. The proteid of leguminous seeds is largely 
in the form of legumin, a casein-like body. 

409. Grading of Grains. — Oats, barley, rye and flax 



300 AGRICULTURAL CHEMISTRY 

are all graded commercially on the basis of their physical 
properties, as weight per bushel, maturity, amount of 
foreign weed seed, and any fungus disease, or injury 
caused by rust or excessive heat. The rules adopted 
by the Minnesota Railroad and Warehouse Commis- 
sion in 1902, for the grading of barley and rye, are as 
follows : 

OATS 

No. 1 white oats shall be white, sound, clean, and free from other 
grain. 

No. 2 white oats shall be seven-eighths white, sweet, reasonably 
clean and reasonably free from other grain. 

No. 3 white oats shall be seven -eighths white, but not sufficiently 
sound and clean for No. 2. 

No. 4 white oats shall be seven-eighths white, but not sufficiently 
sound and clean for No. 3. 

No. 1 oats shall be mixed oats, sound, clean, and reasonably free 
from other grain. 

No. 2 oats shall be sweet, reasonably clean, and reasonably free 
from other grain. 

No. 3 oats shall be all oats that are merchantable and warehous- 
able, reasonably clean, not fit for higher grades. 

No grade oats : All oats that are in a heating condition, too 
musty or too damp to be safe for warehousing, or that are badly 
damaged, and exceedingly dirty, shall be clased as no grade. 

RYE 

No. 1 rye shall be sound, plump, and well cleaned. 

No. 2 rye shall be sound, reasonably clean, and reasonably free 
from other grain. 

No. 3 rye, all rye slightly damaged, slightly musty, or from any 
other cause unfit for No. 2 shall be graded as No. 3. 

No grade rye : All rye that is in a heating condition, too 
musty or too damp to be safe for warehousing, or that is badly 
damaged and exceedingly dirty, shall be classed as no grade. 



OATS, BARLEY, RYE, ETC. 301 

BARLEY 

No. 1 barley shall be plump, bright, clean, and free from othe r 
grain . 

No. 2 barley shall be sound, of healthy color, not plump enough 
for No. 1, reasonably clean and reasonably free from other grain. 

No. 3 barley shall include all slightly shrunken and otherwise 
slightly damaged barley, not good enough for No. 2. 

No. 4 barley shall include all barley fit for malting purposes, not 
good enough for No 3. 

No. 5 barley shall include all barley which is badly damaged or 
for any cause unfit for malting purposes, except that barley which 
has been chemically treated shall not be graded at all. 

No grade barley : All barley that is in a heating condition, 
too musty or too damp to be safe for warehousing, or that is badly 
damaged and exceedingly dirty, shall be classed as no grade 
barley. 

FLAXSEED 

No. 1 northwestern flaxseed shall be mature, sound, dry, and 
sweet. It shall be northern grown. The maximum quantity of 
field, stack, storage, or other damaged seed intermixed shall no^ 
exceed 12.5 per cent. The minimum weight shall be 51 pounds to 
the measured bushel of commercially pure seed. 

No. 1 flaxseed shall be nothern grown, sound, dry, and free from 
mustiness, and carrying not more than 25 per cent, of immature or 
field, stack, storage, or other damaged flaxseed, and weighing not 
less than 50 pounds to the measured bushel of commercially pure 
seed. 

Rejected flaxseed : That which is bin-burnt, immature, field- 
damaged or musty, and yet not to degree to be unfit for storage, 
and having a test weight of not less than 47 pounds to the meas- 
ured bushel of commercially pure seed shall be rejected. 

No grade flaxseed : That which is damp, warm, moldy, very 
musty, or otherwise unfit for storage, or having a weight of less 
than 47 pounds to the measured bushel of commercially pure seed 
shall be no grade. 

(These rules are subject to change from year to year.) 



302 



AGRICULTURAL CHEMISTRY 



Composition of Grains and Seeds. 
(From Jenkins and Winton.) 



Water. 
Per cent. 

Corn, dent 10.6 

" " (max.). 19.4 

" (min.). 6.2 

" flint 11. 3 

" sweet 8.8 

Oats 11.0 

Barley 10.9 

Rye 1 1.6 

Rice 12.4 

Buckwheat 10.9 

Peas 1 10. 1 

Flaxseed 1 5.1 

Millet seed 1 12.5 

Navy beans 12.4 

1 Minnesota analyses. 



Crude 
protein. 
Per cent. 


Ether 
extract. 
Per cent. 


jn ltrogen- 
free ex- 
tract. 
Per cent. 


Crude 
fiber. 
Per cent. 


Ash. 


IO.3 


5-0 


70.4 


2.2 


i-5 


12.8 


7-5 


75-7 


4.8 


2.6 


7-5 


3-1 


65-4 


0.9 


1.0 


IO.5 


5-0 


70.1 


i-7 


1.4 


1 1. 6 


8.1 


66.8 


2.8 


i-9 


11. 8 


5-0 


59-7 


9-5 


3-o 


12.4 


1.8 


69.8 


2.7 


2.4 


10.6 


i-7 


72.5 


i-7 


1.9 


7-4 


0.4 


79.2 


0.2 


0.4 


10.5 


5-4 


69.6 


2.1 


i-5 


21.6 


1.0 


58.2 


5-7 


3-4 


27-5 


38.6 


17.9 


7-4 


3-5 


10.6 


3-9 


61. 1 


8.1 


3-8 


22.2 


1.4 


53- 1 


7.2 


3-7 



CHAPTER XXXII 
Mill and By-Products 

410. Sources. — In the milling of wheat, the preparation 
of cereal foods, the malting of grains, the extracting of 
oil from seeds and the manufacture of starch and glucose, 
various by-products are obtained which are used for the 
feeding of animals. 

411. Wheat By-Products. — In the milling of wheat, 
about 72 per cent, of the grain is returned as straight and 
patent grade flours, 2.5 to 3 per cent, as low-grade and 
red-dog, and 25 per cent, as wheat-offal — bran, shorts and 
germ. The separation of the wheat kernel into these 
various products is a mechanical operation effected by 
rolls for the reduction of the grain, and sieves and bolting- 
cloths for the separation of the various products. The 
standard grades of flour and the percentage amounts of 
each recovered in milling are approximately as follows : 

Per cent, of 

cleaned wheat 

recovered. 

i. First patent • 56.0 

2. Second patent 60.8 

3. Straight or standard patent 72.1 

4. First clear or first bakers 1 i.S 

5. Second clear or low-grade 0.5 

6. Red-dog 1.9 

7. Shorts middlings 1 1.6 

8. Bran 13.4 

(Straight grade flour is composed of first and second patents and 

first clear grade. ) 



304 AGRICULTURAL CHEMISTRY 

412. Wheat Bran is composed mainly of the outer 
layers of the wheat kernel separated in the process of 
milling (see Fig. 88). Along with the outer layers, some 
of the floury portion and aleurone cells are removed, and 
find their way into the bran and fine bran or shorts. Wheat 
bran varies in chemical composition and feeding value 
according to the composition and character of the wheat 
used and the process of milling employed. Wheat bran 
may contain as low as 14 and as high as 18 per cent, of 
crude protein ; average bran contains about 16 per cent. 
Two samples of bran may contain the same percentage 
amount of protein and not have the same feeding value. 
For example, one wheat containing 13 per cent, protein 
can be exhaustively milled and yield a bran of 16 per 
cent, protein while another wheat with 14 per cent, 
imperfectly milled may yield a bran with 16 per cent, 
protein. While both brans contain the .same amount 
of crude protein, 16 per cent., the second sample would 
contain the larger amount of available non- nitrogenous 
nutrients and with the same per cent, of crude protein 
would produce better results in feeding than the first 
sample. The lower grades of flour are frequently left in 
the bran, imparting a high nutritive value. Spring wheat 
bran usually contains more protein than winter wheat 
bran. This is due largely to the more nitrogenous char- 
acter of the spring wheat. Pure bran should be free from 
weed seeds and all foreign matter. Bran occupies a high 
position among animal food-stuffs. It is bulky in nature 
and can be fed in comparatively large amounts without 
injury to animals. Director Henry in "Feeds and Feed- 



MILL AND BY-PRODUCTS 305 

ing" states : ' ' Next to corn, wheat bran is the great cow 
feed of this country. Rich in ash and protein, carrying a 
fair amount of starchy matter, its light chaffy character 
renders it the natural complement of heavy cornmeal. 
Though its nutritive constituents approximate those of 
cottonseed meal, it mixes well with that feed, causing it 
to lie more lightly in the stomach. 

' ' The large amount of mineral matter in bran is another 
factor of much importance in milk production. In milk 
there is much mineral matter, placed there for the frame- 
work of the calf, and bran supplies this more abundantly 
than most feeding-stuffs. 

"Middlings, like bran, are extensively fed to dairy- 
cows. Being themselves heavy in character, they do not 
mix well with heavy feeds like cottonseed-meal and corn- 
meal. Dairymen will find middlings much relished by 
cows and yielding satisfactory returns. Bran and mid- 
dlings are conceded by all who have fed them to favorably 
affect the flow of milk. Cows may be fed as much as 6 
to 8 pounds of bran daily and from 4 to 6 pounds of mid- 
dlings. Bran was at first regarded with favor only by 
dairymen. Gradually the steer feeder is learning its 
value in connection with other grain in the feed box. 
Because of its bulky character and its cooling, slightly 
laxative properties, bran is a most excellent diluent for 
cornmeal, cottonseed-meal and other heavy food sub- 
stances. Where it can be obtained at a reasonable price, 
the stockman will find much satisfaction in mixing one- 
third its weight of bran with cornmeal." 

In commenting upon the feeding value of bran, Jordan, 



306 AGRICULTURAL CHEMISTRY 

in the "Feeding of Animals," states: "No commercial 
feeding-stuffs are regarded with greater favor, or are more 
widely and largely purchased by American feeders than 
the by-products from milling wheat. Wheat bran and 
middlings are cattle foods of standard excellence, whether 
we consider composition, palatableness or their relation 
to the quality of dairy products." 

413. Wheat Shorts consist of those outer portions of 
the wheat kernel which contain less crude fiber, protein, 
and ash than the parts which make up the bran. This 
product is practically the fine bran subjected to more com- 
plete pulverization and mixed with some low-grade flour. 
It is more variable in composition than bran, but for 
some purposes, as pig-feeding, is more valuable. When 
the wheat germ is added to the shorts, the product is 
called middlings or shorts middlings. When used in this 
connection, the term middlings means an entirely differ- 
ent product from the middlings obtained by the stone 
process of flour production ; such middlings are now re- 
duced and recovered in the patent grades of flour. Shorts 
middlings are richer in protein and fat than ordinary 
shorts. When the weed seeds, and the screenings and 
scourings of the wheat are mixed with the shorts, a prod- 
uct known as shorts feed is obtained. This practice, 
however, is not generally followed. 

414. Wheat Germ is exceedingly rich in both protein 
and fat. About 8 per cent, of the wheat kernel is re- 
moved as germ in the process of milling, because if added 
to the patent flour, it imparts poor keeping qualities and 



MILL AND BY-PROL-UCTS 307 

its proteid is not suitable for bread- making purposes. 
Wheat germ contains a number of nitrogenous and phos- 
phorized compounds which can be extracted along with 
the oil, and which are laxative in character. On this 
account, pure wheat germ cannot be fed alone or in large 
amounts in a ration, but when combined with other foods, 
it is valuable. 

415. Wheat Screenings are a mixture of various seeds 
with occasionally the broken and shrunken wheat kernels, 
and vary in composition and food value with the different 
kinds of weed seeds present. When fed, they should be 
finely ground so as to prevent the introduction of foul 
weeds on the farm. During recent years, mustard seeds 
have been removed from wheat screenings and sold as a 
separate product, the oil which they contain being ex- 
tracted and used commercially. 

416. Linseed Meal. — When the oil is extracted from 
flaxseed, linseed cake is obtained which, when ground, 
forms linseed meal. Pure linseed meal should contain 
36 per cent, crude protein. The darker-colored meals are 
those which contain moist oil. Linseed meal is a con- 
centrated nitrogenous animal food and is valuable for the 
feeding of all kinds of farm animals. When used, it 
should be combined with other foods. Linseed meal is 
occasionally adulterated with flax screenings. Hence, in 
its purchase, if adulteration is suspected, preference 
should be given to the nut rather than to the fine ground 
meal. The cake itself is not adulterated because weed 
seeds and impurities must be removed in order to produce 



308 AGRICULTURAL CHEMISTRY 

a good quality of oil. When the oil is removed from the 
flaxseed by naphtha and other chemicals, the product is 
called ' ' new process linseed meal ' ' which differs from 
pressure process meal by having the oil more thoroughly 
extracted and by containing a larger amount of crude 
protein. 

417. Cottonseed Cake and Meal obtained from cotton- 
seed after the removal of hulls and the extraction of the 
oil, are concentrated nitrogenous foods. The meal is 
lemon-yellow in color and is characteristically rich in 
crude protein and ether extract. It contains somewhat 
more crude protein than linseed meal. Cottonseed meal 
is a concentrated nitrogenous food and can be fed, when 
properly combined with other foods, to sheep and beef 
and dairy animals. It cannot safely be fed in large 
amounts nor for a long period to swine. When used in 
a dairy ration as the principal food, it influences the char- 
acter of the butter-fat, producing butter with a high melt- 
ing-point. 

418. Oat Feed is a product obtained in the manufacture 
of oatmeal. It is variable in composition and consists of 
light-weight oats mixed with oat hulls. Oat hulls have 
about the same composition and feeding value as oat 
straw and are frequently used for the adulteration of ani- 
mal foods. In the purchase and use of oat feeds, par- 
ticular attention should be given to their composition. 
High-grade oat feed is valuable, but when consisting of 
any appreciable amount of oat hulls, the food value is 
proportionally lessened. 



MILL AND BY-PRODUCTS 309 

419. Gluten Meal is a by-product obtained in the manu- 
facture of glucose. The soaked corn is broken open 
and the germ is liberated and floated off with water. 
The oil from the germ is extracted and the germ cake 
sold as a commercial product or used for mixing with 
other foods. The starch and gluten of the corn are sepa- 
rated by mechanical means. The starch being heavier 
separates and settles, while the gluten is floated off with 
water. The gluten product is dried, ground and sold as 
gluten meal which usually contains about 35 per cent, of 
protein and 3 per cent, of fat. Gluten feed contains the 
corn hulls or bran along with the gluten meal. The 
hulls reduce the proportion of protein. Gluten feed 
usually contains about 25 per cent, of crude protein but 
is quite variable in composition. 

420. Malt Sprouts. — When barley is subjected to the 
malting process, germination takes place, which results 
in changing the starch of the grain to maltose. The 
plantlets or sprouts are removed, dried and sold as malt 
sprouts. They are nitrogenous in character and contain 
about 22 per cent, of crude protein, the larger portion of 
which is present in soluble form. Malt sprouts are valu- 
able for feeding sheep and beef and dairy stock. 

421. Miscellaneous By- Products. — There are a large 
number of miscellaneous by-products used for the feeding 
of animals, as rye bran, buckwheat middlings, palm-nut 
meal, hominy chops, etc. Their composition and general 
feeding value can be determined from the table of anal- 
yses at the close of the chapter. 



3io 



AGRICULTURAL CHEMISTRY 



422. Inspection of Feeding-Stuffs. — During recent 
years, many of the states have passed laws regulating the 
inspection and sale of animal feeding-stuffs. The object 
of such laws is to prevent adulteration of animal foods by 
requiring manufacturers and dealers to guarantee the per- 
centage amounts of crude protein and fat. Many of the 
European countries have had such laws in force for a 
number of years. It is noticeable that in those countries 
and states where feeding-stuffs are subjected to in- 
spection, the quality is better than where they are not 
inspected. 

Experiment 73. — Graphic composition of foods. Make a draw- 
ing of some human or animal food material and indicate graphically, 
the percentage amount of the different nutrients. If a hundred 




Fig. 91. — Graphic composition of foods. 

millimeter rule is used in the construction of the drawing, each 
linear millimeter will correspond to 1 per cent. If a food contains 
12 per cent, water, 12 millimeters are measured off to represent the 
water in the material, and so for each class of nutrients, an area 
corresponding to its percentage amount. 



mill and by-products 311 

Composition of Mill and By-Products 



Per 
cent. 

Linseed meal (old process). 9.20 

" " (new process) 10.10 

Cottonseed-meal 8. 20 

Malt sprouts 10.20 

Corn and cob meal 15.10 

Gluten meal 9.60 

" feed 7.80 

Oat feed 7.70 

" hulls 7.30 

Sugar-beet pulp 1 8S.53 

Rye bran 11.60 

Buckwheat middlings 13.20 

Palm-nut meal 8.30 

Hominy chops 11. 10 

Apple pomace 76. 70 

Wheat bran, winter 12.30 

" " spring n.50 

" shorts 11.80 

" screenings 11.60 

Meat scrap 1.33 

Wheat flour (Minn.) 11.90 

Cornmeal 15.10 

Corn flour 12.57 

Buckwheat flour 14.60 

Oatmeal 7.90 

1 Dry matter basis. 



< 


'C 


u 


*0 u 
3 V 

O<0 


v 

h v 


"3 

ft 


Per 
cent. 


Per 
cent. 


Per 
cent. 


Per 
cent. 


Per 
cent. 


5-70 


32.90 


8.90 


35.40 


7.90 


5- 80 


33- 20 


9-50 


38.40 


3.00 


7.20 


42.30 


5.60 


23.60 


13.IO 


5-70 


23.20 


IO.70 


48.50 


I.70 


I.50 


8.50 


6.60 


64.80 


3-50 


O.70 


29.40 


I.60 


52.40 


6.30 


I. IO 


24.OO 


5-3° 


51.20 


10.60 


3-70 


16.OO 


6.IO 


59-40 


7.10 


6.70 


3-30 


29.70 


52.IO 


1. 00 


4-85 


9-45 


22.40 


62.62 


0.68 


3.60 


14.70 


3-50 


63.80 


2.80 


4.80 


28.90 


4.IO 


41.90 


7.10 


3-70 


14.40 


21.40 


38.90 


I3-30 


2.50 


9.80 


3- 80 


64.50 


8.30 


0.50 


1.40 


3-9° 


16.20 


1.30 


5-90 


16.00 


8.10 


53-70 


4.00 


5-40 


16.10 


8.00 


54.50 


4-5o 


4.60 


14.90 


7.40 


56.80 


4-50 


2.90 


12.50 


4.90 


65.IO 


3.00 


8.03 


57.69 






32-95 


O.40 


12.60 




74-30 


0.80 


I.40 


9.20 


1.90 


68.70 


3-8o 


O.61 


7-13 


0.87 


78.36 


i-33 


I. OO 


6.90 


0.30 


75.80 


1.40 


2.00 


14.70 


0.90 


67.40 


7.10 



CHAPTER XXXIII 
Roots, Tubers, and Fruits 

423. General Composition. — Roots, tubers, and fruits 
contain a large amount of water and a small amount of 
dry matter. The dry matter is composed mainly of non- 
nitrogenous compounds as starch and sugar. These foods 
all contain small amounts of nitrogenous compounds of 
which the larger portion is in amide and non-proteid 
forms. Organic acids in small amounts and essential 
oils are characteristic features. 

424. Potatoes contain about 75 per cent, of water. 
The dry matter is largely starch. About half of the 
nitrogen is present as proteids of which the larger portion 




S3 Protein. 13 Pat ■ Indigestible. 

Fig. 92. — Composition of potatoes. 

is in the form of soluble albumin. The amount of fat is 
small, less than a tenth of i per cent. Potatoes contain 
but little cellulose. Tartaric and other organic acids, 



ROOTS, TUBERS, AND FRUITS 



313 



pectose substances, and other compounds are present in 
small amounts. When potatoes are stored for any length 
of time and fermentation takes place, a portion of the 
starch is converted into glucose. In storing them, a low 
temperature and good ventilation are necessary to pre- 
vent fermentation. Potatoes are a concentrated non- 
nitrogenous food. 

425. Carrots contain about half as much dry matter as 
potatoes. There is approximately the 
same amount of water as in milk, viz., 87 
per cent. The 12 per cent, of dry matter 
is nearty half sugar, 3 per cent, being 
fruit sugar and 3 per cent, other 
sugars. Carrots contain 1 . 20 per cent, of 
total nitrogenous compounds given as 
crude protein in tables of analyses, of 
which 40 per cent, is protein. There is 
more fat in carrots than in potatoes. 

426. Parsnips contain more dry mat- 
ter than carrots and have nearly the same 
amounts of nitrogenous compounds, fat 
and fiber, but less sugar and more starch. 
They have about the same general food 
value as carrots. 

427. Mangel wurzels contain more 
water and less dry matter than carrots. 
The dry matter, however, is richer in 
nitrogenous compounds than that of car- 
rots, parsnips, potatoes or beets, which makes the mangels 




I.FIBER. STARCH, 
FAT ETC. 

Z. SUGAR 

J. PROTEIN +NI- 
TROGENOUS MAT- 
TER 

4.ASH. 

Fig. 93.— Composi- 
tion of carrots. 



314 AGRICULTURAL CHEMISTRY 

a better balanced food. The 10 per cent, of dry matter 
in mangels is a little more than half starch and contains 
about 1.40 per cent, of crude protein of which half is pro- 
tein. Mangels also contain about 1 per cent, each of ash 
and fiber and a small amount of fat. 

428. Apples vary in composition with the variety and 
physical characteristics. They contain from 10 to 16 per 
cent, solids, of which 75 per cent, is sugar or allied carbo- 
hydrates, and about half a per cent, each is fat and protein. 
Among the organic acids, malic predominates. The 
flavor and special characteristics depend upon the relative 
amounts of the different sugars, as sucrose, levulose and 
dextrose, and the organic acids and essential oils which 
the apples contain. It is these compounds which give 
individuality to apples. 

429. Oranges contain from 10 to 15 per cent, of solid 
matter, the larger portion ( 80 per cent. ) being sugar. 
The citric acid content ranges from 1 to 2.5 per cent, in 
different varieties. The amount of protein, fat and fiber 
is small. The ash or mineral matter averages about one- 
half per cent, and is composed mainly of potash and lime 
with smaller amounts of other compounds. The iron and 
sulfur content in some kinds of oranges is larger than is 
ordinarily found in other fruits. In average oranges, 
the physical composition is as follows : Rind, 20 to 30 
per cent. ; pulp, 25 to 35 per cent. ; and juice, 35 to 50 
per cent. 

430. Lemons differ from oranges in containing larger 
amounts of citric acid and smaller amounts of sucrose, 



ROOTS, TUBERS, AND FRUITS 315 

levulose and dextrose. The average composition of 
lemons is as follows : 

Physical composition. Chemical composition. 

Per cent. Per cent. 

Rind 25 to 35 Solids 10 to 12 

Pulp 25 to 35 Sugar 2 to 4 

Juice 40 to 55 Citric acid 6 to 9 

The ash of the lemon is somewhat similar in composition 
to the ash of the orange but is present in larger amount. 

431. Strawberries are characterized by containing a 
high per cent, of water (90 to 92 per cent.). Sugar and 
malic acid are the materials present in largest amounts 
while protein, fat, ash and fiber form but a small part of 
the composition. Coloring materials and essential oils 
are also present in small amounts. While strawberries 
are valuable as a food adjunct, they do not supply any 
appreciable amount of nutrients. It has been estimated 
that it would require 13 pounds of strawberries to supply 
the carbohydrates needed for a daily ration to say nothing 
of the protein which would require 65 pounds additional. 
The malic and other acids present are valuable because 
of their antiseptic properties which, added to the appear- 
ance and palatability, make strawberries a valuable food 
adjunct. 

432. Grapes vary in composition according to variety. 
They contain from 15 to 20 per cent, of solid matter. 
The juice contains from 10 to 15 per cent, or more of 
sugar in the form of sucrose, levulose and glucose. The 
tartaric acid, which is found in grapes in larger amount 
than in other fruits, ranges from 1 to 1.5 per cent. 
Grapes do not contain any appreciable amount of protein 



316 AGRICULTURAL CHEMISTRY 

or fat and while they add some nutrients, as sugar, to a 
ration, they do not contribute any large amounts. There 
is some food value but it is not as high as is occasionally 
claimed for them. Their value, as is the case with other 
fruits, is in palatability and indirectly aiding in digestion 
and adding value to other foods. 

433. Olives, when fully matured and fresh, contain about 
15 per cent, of oil. When preserved green, there is 
considerably less. Olives also contain small amounts of 
other compounds and essential oils. Pure olive oil is a 
valuable food, but is frequently adulterated with refined 
cottonseed and other vegetable oils. Olive oil is slightly 
laxative in character and assists mechanically in the 
digestion of foods by preventing compaction of feces in the 
intestines. 

434. Dried Fruits. — In preparation for the market, 
many fruits are preserved by drying. The dried fruit 
has a somewhat different composition from the fresh 
fruit because of chemical changes which take place dur- 
ing the drying process and the slight loss of volatile and 
essential oils. Dried fruits, when free from preservative 
agents, are valuable, and can be used to advantage if 
fresh fruits are not obtainable. 

435. niscellaneous Fruits. — Since the list of fruits 
that could be discussed is so large, only a few examples 
have been considered. For additional information upon 
the subject, or for data upon fruits not given, the student 
is referred to the bulletins of the California Experiment 
Station. 



ROOTS, TUBERS, AND FRUITS 317 

436. Food Value. — When judged only on the basis of 
the nutrients present, many vegetables and fruits would 
be assigned a low place in the list of foods as they con- 
tain only comparatively small amounts. Most fruits are 
used in the dietary, not so much with the view of sup- 
plying nutrients as for other purposes. The organic 
acids, essential oils, and soluble mineral compounds, to- 
gether with the digestible form in which the nutrients 
are present are the factors which give fruits their unique 
value. The organic acids and essential oils impart pala- 
tability and assist functionally in the digestive process. 
Some fruits, as figs and prunes, contain chemical com- 
pounds which are laxative in character. In the human 
ration, fresh fruits are as essential and occupy the same 
position as do roots and vegetables in animal rations. 



CHAPTER XXXIV 
Fermentation 

437. Insoluble Ferments. — Fermentation is a chemical 
change produced by a class of bodies called ferments. Insol- 
uble or organized ferments are single celled, microscopic 
plants which have a definite structure. Many of them 
are bacteria while others are low forms of plant life. 
Nearly all secrete definite chemical products capable of 
producing fermentation. The insoluble or organized fer- 
ments are composed mainly of nitrogenous compounds 
but also contain non-nitrogenous and mineral matter. 
Some, as the tubercular organism, contain cellulose. 

438. Soluble Ferments or Enzymes. — Enzymes are 
organic compounds, secreted by cells, and have the 
property of producing chemical changes. They are also 
called soluble ferments, chemical ferments, and diastases. 
There are a great many different kinds of soluble ferments 
some of which, as diastase and maltase, are capable of 
acting upon carbohydrates, while others, as pepsin and 
pancreatin, act upon proteid bodies. Enzymes produce 
chemical change without entering into the composition 
of the substance or giving up any of their own material 
to the reacting compounds. A small amount of diastase 
will change a large amount of starch to soluble forms 
without losing its power of action. The enzymes are all 
soluble in water and are precipitated with strong alcohol. 
Their action is not generally retarded by antiseptics and 
chemicals which are capable of destroying organized fer- 



FERMENTATION 319 

ments. When seeds are soaked in water, the diastase 
and proteose enzymes are extracted and if precipitated 
with alcohol and recovered, they appear as a light gray 
powder. An organized ferment is a low form of plant, 
while a soluble ferment is a chemical compound. 

439. Aerobic and Anaerobic Ferments. — Ferments 
which require oxygen for their existence are aerobic 
while those which are capable of working in the absence 
of oxygen are anaerobic. The aerobic ferments produce 
carbon dioxid, water, ammonia and hydrogen sulfid as 
final products, while the anaerobic ferments usually pro- 
duce intermediate products as organic acids. 

440. Conditions Necessary for Fermentation. — The 

conditions necessary for fermentation are : ( 1 ) Moisture, 
(2) favorable temperature, (3) a ferment body, and (4) 
a fermentable substance. Moisture is necessary in order 
that the chemical changes may take place. During 
fermentation water frequently enters into the chemical 
reaction, as in hydration changes, and is also neces- 
sary as a medium of exchange for the chemical products 
during the reaction. The most favorable temperatures 
for fermentation are between 15 and 6o° C. Below 
zero and above the boiling-point of water, ferments are 
inactive. Some ferments require a different temperature 
for activity than others. A ferment body is always neces- 
sary in order to start the fermentation change, and in the 
absence of a ferment either organized or unorganized, no 
fermentation can take place. A fermentable substance, 
with the right kind of ferment to act upon it, is also req- 



320 AGRICULTURAL CHEMISTRY 

uisite, as a ferment which acts upon one class of bodies is 
incapable, unaided, of acting upon others ; for example, 
the peptic ferment is incapable of changing starch to 
soluble forms. When a substance is freed from all fer- 
ments and is protected from outside sources of contami- 
nation, it is in a sterile condition. Many forms of fer- 
mentation are produced by the spores of organized fer- 
ments gaining access to a material along with dust particles 
carried in the air. In the preservation of food, a knowl- 
edge of the conditions requisite for fermentation is made 
use of. The products formed by ferments are numerous, 
as there are ferment bodies capable of acting upon all forms 
of organic matter. Some of the ferments assist in the 
digestion of food and in the preparation of food products, 
while others take an important part in every-day life 
affairs, and in agriculture as in the liberation of plant 
food. The growth of plants, the preparation of foods, 
and their digestion, and the manufacture of food products 
all depend largely upon fermentation. 

441. Soil Ferments.— In the growth of plants, fer- 
ments take an important part, both in the preparation of 
the plant food and in the chemical changes which take 
place within the plant. Disintegration of the mineral 
food of the soil is assisted by ferment action. The nitroge- 
nous food of the plant is all prepared in the soil by fer- 
ments. The subject of soil ferments is briefly considered 
in the ' ' Chemistry of Soils and Fertilizers. ' ' 

442. Ferments in Seeds. — In the seeds of plants, par- 
ticularly matured grains, there are a number of ferments 
which take an important part in the process of germina- 



FERMENTATION 3 2 1 

tion. These ferments change the insoluble nitrogenous 
and non-nitrogenous compounds to soluble forms, which 
are utilized by the young plant as food. If a seed were 
deprived of all of its soluble ferments, it would fail to 
germinate. 

Experiment 74. — Action of malt on starch. Crush in a mortar 
twenty malted barley kernels, transfer to a test-tube, and add 
15 cc. water. After twenty -four hours, filter off the solution, and 
add it to a flask containing 2 grams of flour and 100 cc. water. 
Place the flask in the desk for twenty-four hours ; then filter off 
the solution and test a portion for starch with iodin, as in Experi- 
ment 45. Test another portion for glucose with Fehling's so- 
lution, as in Experiment 48. 

Questions. ( 1 ) What is malted barley ? ( 2 ) What did the water 
extract from the barley contain ? (3) What effect did this extract 
have upon the flour? (4) What did the tests with iodin and Feh- 
ling's solution show? (5) Would flour treated with water instead 
of malt extract give the same result ? 

443. Ferments in Bread-flaking. — The yeast plant 
employed in bread-making secretes a number of soluble 
ferments which produce the desired chemical changes. 
The diastase ferment changes the starch to soluble forms, 
the alcoholic ferment produces alcohol and carbon dioxid 
gas, which expand the dough and make the bread light, 
and acid ferments produce acids, which combine with the 
gluten proteids and modify their character. In short, 
bread-making is simply a series of chemical changes in- 
duced by soluble ferments. 

Experiment 75. — Alcoholic fermentation. Weigh 10 grams 
of flour into a flask, add 50 cc. water and a small piece of yeast 
(one-tenth of a cake). Connect the flask by means of a delivery 
tube with the Woulff bottle containing enough clear lime water to 



322 AGRICULTURAL CHEMISTRY 

cover the end of the tube. Place the flask on a warm sand-bath, 
below 85 F., for half an hour. Observe the bubbles of gas given 
off and the precipitate formed in the lime water. Do not overheat 
the sand-bath. 

Questions. (1) What is yeast and what does it contain? (2) 
What caused the gas to be given off? (3) From what was the gas 
formed? (4) Write the reaction with Ca(OH) 2 . (5) What be- 
comes of the alcohol ? 

444. Ferment Action and Food Digestion. — The di- 
gestion of food is carried on largely by the action of solu- 
ble ferments. The digestive tract secretes a number of 
these, which act upon the insoluble nutrients and change 
them to soluble forms. In fact, the digestion of food is 
dependent upon the action of the different ferments in the 
digestive tract, as ptyalin in the saliva, pepsin in the 
stomach, pancreatin in the duodenum, and diastase and 
other ferments in the intestines. 

445. Ferments and Food Preservation. — Preservation 
of food is dependent upon prevention of ferment action. 
The low temperature of cold storage is unfavorable to 
the development of ferments. Sterilization is likewise 
unfavorable. By means of heat, cold storage, chemicals, 
and protection from the spores in the air, perishable food 
products are preserved. Some ferments, however, are 
not destroyed either by high or low temperatures. 

446. Ferments in Butter= and Cheese=riaking. — The 

process of butter- and cheese-making is carried on with 
the aid of ferments. Milk itself contains enzymes or 
soluble ferments and, to a limited extent, is itself capable 
of acting as a digestive fluid. The ripening of cream is 



FERMENTATION 323 

the result of the action of the lactic acid ferment which 
changes the lactose (milk-sugar) into lactic acid. In 
cheese-making, the rennet used for coagulating the milk 
contains a number of ferments which take an important 
part in the process. The flavor and odor of butter as 
well as of cheese are the results of ferment action. In 
butter- and cheese-making, it is the object to control the 
action of the desirable ferments and to prevent the unde- 
sirable ones from developing. Ropy milk, red spots in 
cheese, and floating curds in cheese-making, are all 
caused by fermentation. Butyric acid, one of the pro- 
ducts found in foul milk and butter, is caused by the 
butyric acid ferment. Milk is exceedingly susceptible to 
the action of ferments. 

Experiment 76. — Lactic fermentation. Place 5 grams milk-sugar, 
100 cc. water, 5 cc. skim milk, and two or three cr)'stals of sodium 
phosphate in a flask. Leave the flask uncorked in the desk for 
twenty-four hours. Then add a few drops of phenolphthalein in- 
dicator, and determine the amount of lactic acid. 1 cc. alkali = 
0.009 gram acid. 

Questions. (1) Why was milk used in this experiment? (2} 
What was produced from the milk-sugar ? (3) Why was sodium 
phosphate used ? (4) How much acid was produced? 

447. Disease- Producing Organisms. — Many diseases 
are caused by the action of micro-organisms. The dis- 
ease-producing organisms or bacteria invade the body 
and rapidly multiply, living upon the fluids and tissues 
of the body and producing poisonous products. Typhoid 
fever, smallpox, diphtheria, tuberculosis, cholera, and 
many other diseases are caused by specific bacteria. The 
products produced by the action of the organism are 



324 AGRICULTURAL CHEMISTRY 

poisonous, and death is often caused by these toxic 
bodies. Modern methods of sanitation are based upon 
the destruction of disease-producing organisms. 

448. Beneficial Organisms. — While many diseases are 
caused by micro-organisms, not all micro organisms or 
bacteria are injurious. In nearly all foods, there are 
large numbers of bacteria which are of a harmless nature. 
Some are valuable and beneficial to man, particularly 
those which assist in plant nutrition and in the prepara- 
tion and digestion of foods. 



CHAPTER XXXV 
Chemistry of Digestion and Nutrition 

449. Digestion, a Biochemical Process. — In the diges- 
tion of food, the enzymes or soluble ferments take an im- 
portant part. Although digestion is not well understood 
it is known to be largely a chemical process brought about 
by ferment action, and hence is called a biochemical pro- 
cess. The cells in the different parts of the digestive 
tract secrete chemical products which produce chemical 
changes in the food, rendering it soluble so that the vari- 
ous nutrients can be absorbed and used by the body. Any 
compound which is capable of undergoing digestion and 
being utilized for food purposes is called a nutrient. The 
value of any food depends upon the kinds and amounts 
of nutrients present. During the process of digestion, a 
complex series of chemical changes take place, and as a 
result of this process and the assimilation of the food by 
the body, heat and energy are produced. 

450. Digestion Experiments.— The digestibility of a 
food is determined by a digestion experiment. The per- 
centage amount of a nutrient which is digested is called 
the coefficient of digestibility. Not all of the nutrients 
in foods are alike digestible. In clover hay, for example, 
65 per cent, of the organic matter is digested, while 
only 30 per cent, of the crude fiber and 70 per cent, of 
the nitrogen free extract compounds are digested. Each 
compound has its own digestion coefficient. In order to 
determine the digestibility of a food, an animal is fed, for 



326 AGRICULTURAL CHEMISTRY 

a number of days, a weighed amount of food which is 
analyzed. All of the feces or solid excrements produced 
during the experimental period are collected, weighed 
and analyzed. After undergoing the process of digestion, 
the undigested portions of the food along with a small 
amount of digested products are excreted as feces, while 
the liquid wastes of the body contain the products of the 
digested food. From the weight of the food consumed 
and its analysis, the amount of each class of nutrients con- 
sumed is determined. From the dry matter of the feces, 
the undigested nutrients are likewise determined. The 
undigested nutrients subtracted from the total nutrients 
in the food consumed give the amounts digested which 
are calculated on a percentage basis. In the case of clover 
hay, an animal may consume 28 pounds per day containing 
12 per cent, protein ; this is equivalent to 3.36 pounds of 
protein (28 X 0.12 = 3.36). An account is opened with 
the animal in which a charge for 3.3 pounds of protein is 
entered. From the 28 pounds of food, 40 pounds of feces 
or excrements are obtained, as a large amount of water 
is added during the process of digestion. The feces 
which are composed largely of the indigestible portions 
of the food are analyzed and found to contain 20 per cent, 
of dry matter; this is equivalent to 8 pounds of indigesti- 
ble matter yielded by the 28 pounds of clover (40 X 0.20 
= 8). The dry matter is analyzed and found to contain 
15 per cent, of protein ; this is equivalent to 1.2 pounds 
of protein (8 X 0.15 = 1.2). The animal was charged 
with 3.36 pounds of total protein ; 1.2 pounds are found 
to be indigestible, leaving a balance of 2.16 pounds of 



DIGESTION AND NUTRITION 327 

digestible protein, equivalent to 64 per cent, of the total. 
(2.16 -4- 3.36 X 100 = 64). 64 is the digestion coeffi- 
cient of the crude protein in this clover hay. In like 
manner, the digestion coefficients of all of the nutrients 
are determined. 

Example. — From the following figures, calculate the digestion 
coefficients of the organic matter, ether extract, crude fiber and 
nitrogen-free extract of the clover hay. The figures for the com- 
position of clover hay are on the basis of the food as fed, while 
those for the feces are on the basis of the dry matter. 

Composition of clover. Composition of feces 
Hay as fed. (Dry matter.) 

Water 10.00 

Ash 6.90 9.50 

Ether extract 3.10 2.10 

Crude protein 12.00 15.00 

Crude fiber 26.00 30.00 

Nitrogen-free extract 42.00 4340 

451. Caloric Value of Foods. — During the process of 
digestion, heat is produced in proportion to the calories 
contained in the food and the nutrients digested. By 
the caloric value of a food is meant the amount of heat 
measured in calories which the food yields. A calorie is 
the amount of heat required to raise 1 kilogram of water 
i° C. or 1 pound of water about 4 F. The caloric 
value of a food is determined by means of the calorimeter 
(Fig. 94). The calorimeter consists of a steel bomb 
that is placed in a metal cylinder (Q) (Fig. 95). The 
bomb is surrounded by water as indicated in the illus- 
tration, and the cylinder containing the bomb and water 
is placed within a double- walled fiber receptacle ( T 
and U). The bomb itself consists of three parts : The 



328 



AGRICULTURAL CHEMISTRY 



cylinder, which is lined with platinum, the cover, and a 

collar to hold the 
cover in place 
and tightly seal 
the bomb. These 
three parts of 
the apparatus 
are shown in 
Fig. 96. 

The principle 
involved in de- 
termining the 
caloric value of 
a food is simple. 
A weighed 
amount of the 
substance is 
burned in the 
calorimeter and 
the rise in tem- 
perature of the 
water that sur- 
rounds the bomb 
is noted. The 
combustion i s 
carried on in 
oxygen so as to 
be complete, and all means possible are employed to 
secure accuracy of results. The substance to be burned, 
if it is a material like flour, is made into a pellet by 




Fig. 94.— Bomb calorimeter used for determining 
the caloric or heat-producing value of foods. 



pA &=A>p 

s- s- 



y///s//////y////yw/y/AY/////ysM^^ 



'////S///////S/. v//ss//sss//s/Ayvy/sss//////s///s\^\Ys/////s/s/A 




Fig. 95. — Bomb calorimeter, showing interior structure and working parts. 
Atwater, Conn. (Storrs) Agr. Expt. Station, annual report, 1897. 



33° AGRICULTURAL CHEMISTRY 

means of a press. The object of making the material 
into a pellet is that it may form a compact mass and 
burn evenly and not be scattered about in the calorim- 
eter cylinder and be only partially burned. The pellet 
is placed in the small platinum crucible O (Fig. 95). 
This crucible is supported by platinum wires attached 
to the cover of the calorimeter. Above the crucible a 
small coil of fine iron wire is stretched from the 
platinum wires. The cover is screwed tightly upon the 
cylinder of the bomb and oxygen is admitted from 
an oxygen tank under pressure through valve G of 
the cover until a pressure of twenty atmospheres is 
secured, when the valve is securely closed. The bomb 
with the substance to be burned, and charged with 
oxygen is placed in the metal cylinder Q, which con- 
tains a definite amount of water, the temperature of 
which is carefully determined by means of a thermom- 
eter that reads to 0.005 C. The water is kept at an 
even temperature by means of the metal stirrer SS, 
operated by a water motor. A connection is made 
with a storage battery which ignites the small iron wire 
that is suspended above the substance. The burning 
wire falls upon and ignites the material in the platinum 
crucible O. The heat from the combustion of the mate- 
rial raises the temperature of the water in the calorim- 
eter cylinder. A number of readings are taken so as 
to secure the actual rise in temperature, caused by the 
combustion of the substance\ Due allowances are 
made for the heat contributed by the combustion 
of the iron wire, the heat absorbed by the steel bomb 




Fig. 96. — Parts of bomb calorimeter and accessories: A, pellet mold; B, cover to 
bomb ; C, platinum dish, holding substance burned ; D, collar ; E, steel bomb— platinum- 
lined. 



DIGESTION AND NUTRITION 



331 



and. for other factors that are known and under 
control. 

The approximate amount of energy which a food will 
yield can be determined by the use of the following fac- 
tors : Ether extract 4225, and fiber, nitrogen-free ex- 
tract, and crude protein i860. These are the numbers of 
calories which a pound of each of the nutrients yields. 

452. Available Energy of Foods. — Since only a por- 
tion of the nutrients of foods is digesti- 
ble, not all of the total caloric value 
is rendered available to the body. 
The digestion process is more com- 
plete with non-nitrogenous compounds 
than with the proteids. The final 
products of oxidation in the case of 
starch, sugar and digestible carbohy- 
drates are carbon dioxid and water. 
These compounds undergo complete 
combustion. The final products of di- 
gestion of the proteids are amides, the 
larger portion of which is excreted as 
urea in the liquid waste. This com- 
pound, urea, CH 4 N 2 0, does not un- 
dergo complete oxidation in the body. 
If burned in the calorimeter, it would 
yield an additional amount of heat. 
The term available energy of a food 
means simply the total energy avail- Fi s- 97. 

able to the body and measured in calories, 
available energy is obtained by deducting from 




The 
the 



332 AGRICULTURAL CHEMISTRY 

total digestible energy, the calories contained in the 
products, as urea, which are not completely oxidized. In 
the determination of the available energy of foods, the 
principle is the same as that explained in the section re- 
lating to the digestibility of nutrients. The total number 
of calories in a food is determined by the calorimeter ; 
the number of calories in the feces is likewise deter- 
mined and deducted from the total, as well as the caloric 
value of the liquid excrements containing urea. This 
gives the energy of the food available to the animal. 

453- Net Energy of Foods.— In the process of diges- 
tion, particularly of coarse fodders containing much 
crude fiber, energy varying with the density of the tissue 
is required to render the food available to the body. Of 
the total available energy, a portion, and in some cases, 
a large amount is used up in rendering the food available, 
that is, in carrying on the process of digestion. Means 
have been devised whereby the approximate amount of 
work required on the part of the animal to render the 
food available can be determined. When the energy 
used in this way is deducted, it leaves the net energy. 
In the case of coarse fodders, a considerable portion of 
the energy is used up in the digestion of the food leav- 
ing, in some cases, only comparatively little net energy 
while less force is required to digest the grains, and a 
larger amount of energy is available to the body. The 
total, available, and net energy which foods produce are 
important factors because one of the objects of food is to 
supply nutrients for the production of energy. 

454. Digestion of Proteids. — The insoluble proteids 



DIGESTION AND NUTRITION 333 

are acted upon by the pepsin ferment which is present in 
the stomach of animals. Peptones are produced by this 
action. Proteids which escape the action of the peptic 
ferment are later brought into contact with the tryptic 
ferment which is present in the pancreas and lower parts 
of the digestive tract. This ferment acts in an alkaline 
solution while pepsin requires a slightly acid condition. 
The proteids which fail to be digested by either the 
peptic or tryptic ferments are usually expelled as indi- 
gestible proteids. In normal digestion, the fluids of the 
stomach are slightly acid while those of the pancreas and 
intestines are alkaline. For the formation of acids and 
alkalies, sodium chlorid is essential. From this com- 
pound, hydrochloric acid, present in the gastric juice, is 
formed, also the alkaline products in the biliary and other 
fluids. Sodium chlorid is a normal constituent of the 
blood and of many of the vital fluids of the body. 

After serving the various purposes in the body, as noted 
in Section 305, the proteids are expelled as amides in 
either the solid or liquid excrements, the larger portion 
being in the form of urea. From the time the proteids 
are acted upon by the soluble ferments in the digestive 
tract until their products are expelled from the body as 
amides, a large number of intermediate substances are 
formed. Should the proteids fail to undergo normal 
digestion, poisonous products called ptomaines are pro- 
duced. 

455- Digestion of the Carbohydrates. — Digestion of 
the carbohydrates begins with the ptyalin ferment of 
the saliva. Carbohydrate digestion takes place mainly 



334 AGRICULTURAL CHEMISTRY 

in the lower part of the digestive tract where diastase 
and other ferment bodies are secreted which change the 
insoluble carbohydrates to soluble forms. When com- 
pletely digested, carbon dioxid and water are the final 
products. Between the soluble carbohydrates formed by 
the diastase and other ferments and the final products of 
oxidation, carbon dioxid and water, a large number of 
intermediate products are formed. Glycogen is one of 
these bodies and is a carbohydrate present in small 
amounts in the blood but stored up largely in the liver. 
The process of carbohydrate digestion is one in which the 
soluble ferments take an important part, changing the in- 
soluble compounds to soluble and assimilable forms. 

456. Digestion of Fats. — Bile and the intestinal fluids 
are the main factors which assist in the digestion of fats. 
After emulsion or separation into fine particles, the fats 
are changed to glycerin and fatty acids by the action of 
a ferment body. They are then absorbed and undergo 
slow oxidation whereby carbohydrate- like bodies are pro- 
duced. These products then undergo the same general 
changes as the carbohydrates. 

457. Oxygen Necessary for Digestion. — In order that 
digestion may proceed in a normal way, a liberal supply 
of air is necessary to oxidize the nutrients and to prevent 
the formation of poisonous waste products in the body. 
In the absence of a liberal supply of air, normal digestion 
fails to take place. Oxygen is equally as important as 
protein, fat, carbohydrates or water. 

458. Factors Influencing Digestion. —There are a 



DIGESTION AND NUTRITION 335 

number of factors which influence the completeness of 
the process of digestion. Some of these factors are : 
(i) Mechanical condition of the food, (2) combination 
of foods, (3) amount of food consumed, (4) palatability 
of the food, and (5) individuality of the animal. A di- 
gestion coefficient is a variable factor capable of being in- 
fluenced by these and other conditions. 

459. flechanical Condition. — The mechanical condi- 
tion of a food , as fineness of division and density of par- 
ticles, materially influences digestion. As a general rule, 
the finer the division the more complete is the digestion. 
For example, experiments with pigs have shown that 
wheat meal is 10 per cent, more digestible than whole 
wheat. Experiments with other animals, recorded in 
Bulletin No. 77, U. S. Department of Agriculture, Office 
of Experiment Stations, giving the digestibility of Ameri- 
can feeding-stuffs, show equally large differences. The 
finer the division of the particles, the larger is the sur- 
face exposed to the action of the digestive fluids. The 
density of a material also influences its digestibility. Many 
foods contain a fair amount of nutrients, but their me- 
chanical condition is such that the nutrients are not easily 
rendered available because of the presence of a large 
amount of cellulose enclosing and protecting the nutri- 
ents, and as a result, digestion and assimilation fail to 
take place. This is particularly true of many coarse fod- 
ders, as timothy hay and clover when allowed to become 
overripe and fibrous. Digestion experiments with such 
forage, and with that cut in early bloom, show that when 
cut in early bloom, it is more digestible than when over- 



336 AGRICULTURAL CHEMISTRY 

ripe and woody. In the case of human foods also, fine- 
ness of division of the particles favorably affects the com- 
pleteness of the digestion process. Graham or coarsely 
granulated flour, although it contains more nutrients, is 
less digestible and furnishes less total available nutrients 
than finely granulated flour. The advisability of grind- 
ing animal foods depends entirely upon the cost of the 
grinding. Where it can be done on the farm at slight 
expense, it invariably pays to grind grains, particularly 
wheat, barley, millet and others which have a hard seed 
coat. In the feeding of coarse fodders, their mechanical 
condition is an important factor. When shredded corn 
fodder is fed, less energy is required on the part of the 
animal to render the nutrients available. This results in 
the return of a larger amount of net energy from the 
food. 

460. Combination of Foods.- The way in which a 
food is combined and fed in a ration influences its digesti- 
bility. When foods are fed singly, they are not as com- 
pletely digested as when fed in a well-balanced ration. 
For example, experiments have shown that corn alone 
when fed to pigs, is not as completely digested as when 
combined with shorts and other foods. Some foods as- 
sist in the digestion of other foods. Whenever milk is 
added to the ration for pigs, a larger amount of pork is 
secured than when the same amount of nutrients in other 
form is added. The milk assists in the digestion of the 
grains with which it is combined. Exact experiments to 
show the full extent to which one food influences the 
digestibility of another have not as yet been made. In 



DIGESTION AND NUTRITION 337 

the feeding of farm animals, however, the practical results 
which have been obtained show that this is an important 
factor. 

461. Amount of Food Consumed. — In the case of 
human digestion experiments, results have shown that a 
large amount of food is not as completely digested as 
a smaller amount. With farm animals, the experiments 
have not been so decisive. In some cases, large rations 
have been digested as completely as smaller ones. This 
is undoubtedly due to individual differences of animals. 
Excessive amounts of foods, however, have a tendency 
to interfere with normal digestion and the results are not 
as satisfactory as when medium rations are fed. 

462. Palatability.— In order to have the best results, 
the food should be relished by the animals. Palatability 
exerts a favorable influence upon digestibility and also 
upon the returns in animal products. Overripe and 
fibrous fodders are generally lacking in palatability be- 
cause in the later stages of growth, there is a smaller 
amount of the essential oils and other products that im- 
part palatability. The mechanical condition and the 
palatability of coarse fodders are closely associated, and 
the highest degree of digestibility of grains and fodders 
generally accompanies the best mechanical condition. 

463. Individuality. — When a number of animals are 
fed the same ration, individual differences are observed. 
Some animals are capable of digesting all foods more 
completely than are others, and some are capable of 
digesting one food more completely than another food. 



338 AGRICULTURAL CHEMISTRY 

This is due to individuality in digestive power and is 
particularly noticeable in experiments with sheep where 
it has been found that all do not digest the different 
foods equally well. Digestion coefficients obtained in ex- 
periments with one kind of animal, as sheep, are not al- 
ways applicable to other animals. Experiments with 
swine have shown that fiber is not as completely digested 
as with sheep or cows. 

464. Miscellaneous Factors Influencing Digestibility. 
— Experiments in the cooking of foods show that cooked 
foods are no more completely digested by farm animals 
than uncooked foods. Cooking, however, is sometimes de- 
sirable in order to encourage animals to consume a larger 
amount of food. The wetting of food, causing fermenta- 
tion, has been found to be slightly beneficial. How- 
ever, if wetting is practiced, great care should be exer- 
cised to prevent excessive fermentation or the action of 
undesirable ferments. The drying and curing of fodders 
do not appear to exert any unfavorable influence upon 
digestibility provided leaching or excessive bleaching is 
avoided. Green fodders, however, appear to be slightly 
more digestible than cured fodders. In some cases, the 
laxative nature of a food prevents complete absorption of 
the nutrients before the material is expelled from the 
body. 

465. Application of Digestion Coefficients. — Too close 
application of digestion coefficients cannot be made, but 
general comparisons where the experiments have been 
performed under similar conditions are allowable and give 
valuable results. The methods used for the determi- 



DIGESTION AND NUTRITION 339 

nation of digestion coefficients have not been perfected 
and a number of sources of minor error are introduced in 
digestion experiments. In the case of the feces, the 
ether extract contains bile, nitrogen, cleavage products, 
and a number of other non-fatty compounds. Hence the 
figures for the digestibility of the ether extract are in- 
variably too low. Not all of the nitrogen of the feces is 
in indigestible forms, hence there is a tendency for the 
digestibility of the crude protein to be too low, then too, 
it is difficult to assign an absolute nitrogen factor for the 
determination of the crude protein. Notwithstanding 
these known imperfections in determining the digestibility 
of the food, the general results are of great value to the 
farmer as they indicate ways by which the largest re- 
turns, due to the highest degree of digestibility, can be 
secured. Some of the digestion coefficients of the more 
common food materials are given in the following table 
which is taken from Bulletin No. 77, U. S. Department 
of Agriculture, Office of Experiment Stations : 
Digestion Coefficients 



AS 

Green Fodders. 

Timothy 63.5 

Dent corn 67.8 

Oats 59.5 

Red clover 66. 1 

Silage. 

Dent corn silage 65.1 67.1 32.2 49.3 66.7 68.6 80.0 

Flint " " 73.1 76.1 32.9 62.8 75.1 76.9 S1.8 



. 




-si 

eg 




f 




65.6 


32.2 


48.1 


55-6 


65-7 


53-i 


69.8 


35-6 


59-7 


6o.2 


73-7 


74.1 


60.9 


53-4 


71.S 


52.8 


62.6 


69.2 


68.1 


55-o 


67.0 


52.6 


77.6 


64-5 



34Q 



AGRICULTURAL CHEMISTRY 



k. CO 

OS 





a*j 




3 U 




•-a 


y<c 





65.6 67.4 34.3 51.3 70.6 67.4 80.2 



Dent corn silage (imma- 
ture ) 

Cured Fodders. 

Timothy (average) 56.6 

" before bloom .. . 60.7 

" past bloom 53.4 

Dent corn fodder 64.3 

Flint " " 68.6 

Dent and flint (immature) 63.9 

Dent and flint (mature). 68.2 

Corn stover 57.2 

Red clover 57.4 

Grains and Seeds. 

Cornmeal 89.4 

Gluten feed 86.3 

" meal 89.7 

Malt sprouts 67.1 

Wheat bran 62.3 

Oil- Bearing Seeds. 

Cottonseed-meal 73.7 

Linseed meal (old process) 78.7 

Roots. 

Mangels 78.5 

Potatoes (raw) 75.7 

Some of the most noticeable facts observed in the table 
are as follows : The highest degree of digestibility of a 
nutrient is usually obtained with foods which contain the 
largest amount of that nutrient. For example, clover 
hay contains more crude protein than timothy hay, and 
in general, the protein of clover is more completely 
digested than that of timothy. In the case of potatoes, 



57-9 


32.8 


46.9 


52.5 


62.3 


52.2 


61.5 


44.2 


56.8 


58.8 


64-3 


58.4 


54-5 


3°-3 


45-i 


47.1 


60.4 


5i-9 


66.1 


3°-7 


50.4 


62.2 


68.0 


73-6 


71.7 


42.6 


60.0 


74-9 


7°-3 


71.4 


65-7 


37-2 


5i-7 


66.0 


66.2 


72.2 


70.7 


30.6 


56.7 


65.8 


72.2 


73-9 


59-i 


32.6 


35-9 


64.2 


57-9 


70.4 


59-7 


29.1 


58.0 


54-2 


64.4 


55-2 


89.6 




67.9 




94-7 


92.1 


87.3 




85.6 


78.0 


89.2 


84.4 


90.4 




88.2 




89.8 


94-4 


67.2 




80.2 


32.9 


68.1 




65-7 




77.8 


28.6 


69.4 


68.0 


76.1 


23-7 


88.4 


55-5 


60.6 


93-3 


81.2 




88.8 


57-o 


77-6 


88.6 


84.8 


16.4 


74-7 


42.8 


9i-3 




77.0 




44-7 




90.4 


13.0 



DIGESTION AND NUTRITION 34 1 

there is a large amount of nitrogen- free extract compounds 
(starch) s and in the table it will be observed that they are 
more completely digested than the crude protein which is 
present in small amounts. Whenever a food contains 
nutrients in small amounts they are in dilute forms, and 
are not as completely extracted as when present in larger 
amounts. The coarse fodders are not as completely di- 
gested as the grains and milled products. In the coarse 
fodders, the digestion coefficients range from 30 to 65, 
while in grains and milled products, the same nutrient 
ranges in digestibility from 70 to 95. 

466. Digestible Nutrients of Foods. — When the total 
amounts of nutrients in a food are multiplied by the 
digestion coefficients, the available nutrients are secured. 
For example, clover hay contains 12 per cent, crude pro- 
tein which is 60 per cent, digestible. The available or 
digestible crude protein of the clover hay is 7.2 (12 X 
0.6 = 7.2). In like manner, all of the digestible nutri- 
ents of foods are ascertained. The total amount of each 
nutrient is multiplied by its digestion coefficient, which 
gives the total available or digestible nutrients. When 
the average composition of American feeding stuffs and 
the average digestion coefficients are used, the average 
digestible or available nutrients are obtained. Such a 
table is given at the end of the chapter. In the use of 
this table, it should be remembered that the figures apply 
simply to average conditions, and are susceptible to any 
of the influences which affect either the composition or 
the digestibility of foods, and while the amounts of 
nutrients given are fairly constant, they nevertheless 



342 AGRICULTURAL CHEMISTRY 

vary. It is possible by giving due care to the production 
of crops to secure those containing the largest amounts 
of nutrients, and then to feed the crops so as to secure 
the highest degree of digestibility, and more nutrients 
than are given in the tables at the close _of the chapter. 
For example, timothy hay may contain from 5 to 9 per 
cent, protein. That which contains 5 per cent, is less 
completely digested than that containing 9 per cent. 
From the timothy with the highest degree of digestibil- 
ity, there is about 7 per cent, of the protein digestible 
and available, while from that with 5 per cent, of crude 
protein, there is from 2.5 to 3 per cent, available. The 
availability of the other nutrients also is in favor of the 
timothy hay with the larger amount of protein. In the 
feeding of farm animals, particular attention should be 
given to the production of foods which contain the 
largest amounts of nutrients and to combining and using 
them so as to secure the highest degree of digestibility. 
Digestion experiments have pointed out many ways in 
which these objects may be accomplished, and the ex- 
periments are valuable because they indicate ways in 
which the largest returns can be secured from the fodders 
and grains raised and fed upon the farm. 

Experiment jj. — Digestible nutrients of foods. Take the di- 
mensions of one of the measures given out for the experiment and 
calculate its capacity in quarts, dry measure (1 quart = 67. 2 cubic 
inches). Weigh the measure, fill it with oats and weigh again. 
From the tables, calculate the pounds of digestible fat, protein and 
carbohydrates in one quart of each of the foodstuffs. Tabulate 
the results as follows : 




Fig. 98.— Digestion experiments. 



DIGESTION AND NUTRITION 
Digestible Nutrients in Foods. 



343 



Name of food. 


Net weight of meas- 
sure. 


Digestible pounds per quart. 




Grams. 


Pounds. 


Fat. 


Protein. 


C'bhydr'ts. 


Oats 

Shorts 













CHAPTER XXXVI 
Rational Feeding of Animals 

467. Balanced Rations. — A balanced ration is one 
which contains a sufficient amount of nutrients from a 
variety of foods to meet the requirements of the animal. 
Since the different classes of nutrients serve different pur- 
poses in the body, it is the object of rational feeding to 
combine foods so as to supply the nutrients in the right 
proportion for growth and work or production of milk, 
meat or wool. Rational feeding is based upon (1) the 
food requirements of animals, and (2) the amount of di- 
gestible nutrients in foods. The food requirements of 
animals are determined by experiments. 

468. A flaintenance Ration is one which furnishes all 
of the nutrients required for maintaining the weight of 
the body and for performing all of its functions without 
allowing any nutrients for growth, work or other pur- 
poses. A maintenance ration simply sustains the animal 
without making allowance for growth or work. When 
an animal is fed a maintenance ration, it neither gains nor 
loses in weight ; an equilibrium is established between 
the income and outgo of the food. The nitrogen in 
the proteids of the food consumed is all returned in 
the various waste products of the body. The element 
nitrogen is taken as the index for determining the main- 
tenance requirements of animals. When the nitrogen in 
the waste products equals that in the food consumed, and 
no work has been performed, a maintenance ration has 



RATIONAL FEEDING OP ANIMALS 345 

been fed. Growth, work and animal products are all 
produced from the excess of nutrients over those required 
for maintenance purposes. For example, a pig weighing 
200 pounds requires about five pounds of grain per day 
for maintenance. If 5.5 pounds per day are fed, an in- 
crease in weight is secured only from the half pound in 
excess of the maintenance ration. 

469. Standard Rations. — For feeding purposes stand- 
ard rations have been proposed, giving the amounts of 
nutrients required by different classes of animals for dif- 
ferent purposes. These tables have been prepared largely 
as the result of digestion experiments and feeding trials. 
The table in most common use is that prepared by Woulff 
and modified from time to time by various investigators. 
This table is given at the close of the chapter. 

470. Food Requirements of Animals. — In the feeding 
of balanced rations, tables of feeding standards should be 
used largely as guides. It is not necessary that the 
rations should, in all particulars, absolutely conform to 
the standards given. On the other hand, it is not advi- 
sable to have the amounts of nutrients in the rations vary 
in any large degree from the standards. It is difficult to 
specify the amounts of nutrients which, under all con- 
ditions, will meet the food requirements of all classes of 
animals. In previous chapters, it has been shown that 
the composition of forage crops is subject to variation as 
is also their digestibility. Hence, tables giving the 
amounts of digestible nutrients are only approximately 
correct, and if assumed for all fodders and conditions, the 
calculated amounts of nutrients would, in some cases, 



346 AGRICULTURAL CHEMISTRY 

exceed and in others fall short of the standards given. 
On this account, it is not possible to adhere too closely to 
fixed rules in the rational feeding of farm animals. 
When foods containing the largest amounts of nutrients 
are produced and so fed as to secure the highest degree 
of digestibility, smaller amounts are required than when 
foods low in available nutrients are used and injudiciously 
fed. 

471. Food Supply at Different Stages of Growth. — 
The amount and nature of the food consumed should vary 
with the period of growth. Rations for young and grow- 
ing animals should contain a larger amount of protein 
and a smaller amount of non-nitrogenous compounds 
than rations for mature animals. This is because more 
food is required for building purposes in the early stages 
of growth, than in later stages when more is required 
for heat and energy. These facts may be observed from 
the table of feeding standards. For example, a calf 
three months old and weighing 150 pounds requires per 
day 0.6 pound digestible protein and 2.4 pounds diges- 
tible non-nitrogenous compounds. When the animal is 
a year old and weighs 500 pounds, it requires 1.3 pounds 
of digestible protein and 6.9 pounds of digestible non- 
nitrogenous compounds. The animal has increased in 
weight more than three times while the increased demand 
for digestible protein is only about twice as great, but 
for the non-nitrogenous compounds four and one-half 
times as great. 

When an excessive amount of starchy and non-nitro- 
genous foods is fed to a young and growing animal, 



RATIONAL FEEDING OF ANIMALS 347 

there is a tendency toward the production of a poor mus- 
cular and bony framework and premature fattening. To 
produce balanced growth in young animals, careful 
attention should be given to the amount and nature of 
the nutrients supplied in the food. 

472. Food Requirements of Horses. — In feeding work 
horses, the object is to provide available nutrients for the 
production of energy because it is the energy from the 
food which enables the horse to do his work. Experi- 
ments have shown that for maintenance purposes, a 
1000-pound horse requires about 17.5 pounds of hay per 
day containing a half pound of digestible protein and 7 
to 7.5 pounds of digestible non- nitrogenous compounds. 
Such a ration does not provide any nutrients for work. 
In the table at the close of the chapter are given the 
amounts of nutrients required for average work. Any 
increase in work should be followed by a corresponding 
increase of food. Average work is best accomplished 
with a ration containing 22 to 24 pounds of dry matter 
per day of which about 1.8 pounds are digestible protein 
and n to 1 1.5 pounds are digestible nitrogen-free extract. 
It is estimated that about one-third of the energy derived 
from the food is utilized as useful energy in the perform- 
ance of work. The best results are obtained when an 
even draft is made upon an animal, as experiments have 
shown that less energy is required for average work con- 
tinuously than for severe work for a short time fol- 
lowed by rest. 

473. Selection of Food for Horses. — For light work, 5 
to 7 pounds per day of mixed grains are usually sufficient 



348 AGRICULTURAL CHEMISTRY 

if combined with 12 to 15 pounds of coarse fodder as 
timothy hay. For average work, however, more food is 
required, and the amount of grain should be about equal 
in weight to the coarse fodder. For heaviest work, the 
grain should exceed the fodder in weight. Pure clover 
hay, on account of its mechanical condition, is not suita- 
ble for the feeding of horses. Timothy hay, blue grass 
and the different varieties of prairie hay are all suitable, 
if cut and cured when mediumly ripe. Early cut 
fodders are not as satisfactory for the feeding of horses 
as for the feeding of other kinds of animals. There 
is a tendency to confine the ration of horses too largely 
to one grain, oats, which usually makes an expensive 
ration. Experiments have shown that a larger variety 
of foods is desirable. Corn, barley, ground wheat, bran 
and other milled products are all suitable for forming part 
of the ration for work horses. For purposes of variety, 
carrots or potatoes in small amounts may be fed. Oil 
meal to the extent of about one-fourth pound per day is 
also valuable. For average work, the grinding of grains 
is not necessary ; for hard work, coarse grinding results 
in a return of a larger amount of the net energy of the 
foods. 

474. Foods Required for Beef Production. — Accord- 
ing to the table of feeding standards from 25 to 30 
pounds dry matter containing 2.5 to 3 pounds digestible 
protein, and about 15 pounds digestible carbohydrates are 
required for a 1000-pound animal. As pointed out by 
Jordan, in the "Feeding of Farm Animals," these stand- 
ards are too hia:h for economic feeding:. As the result of 



RATIONAL FEEDING OF ANIMALS 349 

feeding trials, 15 pounds digestible organic matter per 
day for a 1000-pound animal have been found sufficient. 
A ration containing 15 pounds digestible dry matter, 
about 1.80 pounds digestible protein, 1 3 pounds digestible 
nitrogen-free extract compounds and 0.7 pound digestible 
ether extract was found satisfactory. When too scant an 
amount of protein is supplied in a ration, the meat is of 
poorer quality than when more is available so as to pro- 
duce a normal amount of circulatory proteids in the 
system. In beef production, the aim should be to supply 
sufficient available protein for maintenance purposes, and 
a small amount for the other needs of the body, the fat 
being produced from the less expensive nutrients as car- 
bohydrates and ether extract. When the fat is produced 
from an excess of protein in the food, the cost of produc- 
tion is unnecessarily large. The protein supply in beef 
production should vary with the stage of fattening. Ex- 
periments at the PennsylvaniaStation show that 0.42 pound 
digestible protein, 6.77 pounds digestible non-nitrogenous 
compounds and 0.13 pound digestible ether extract are 
required for maintenance purposes. At different stages 
of growth, different amounts of food are required to pro- 
duce a pound of gain. This fact is particularly notice- 
able in experiments at the Kansas Station from which the 
following data are taken : 

Grain required for 
1 pound gain. 

After 56 days 7.30 

After 84 days 8.07 

After 122 days 8.40 

After 140 days 9.01 

After 168 days 9.27 

After 182 days 10.00 



35° AGRICULTURAL CHEMISTRY 

In the production of beef, palatability of the ration is 
an important factor ; this is best secured by combining a 
number of grains and coarse fodders. 

475. Selection of Foods for Beef Production. — Foods 
which are valuable for milk production are likewise valu- 
able for beef production ; bran, oil meal, cottonseed meal, 
corn, barley, shorts, middlings and screenings are among 
the best grain and milled products for beef production. 
Pasture grass, clover hay, alfalfa, corn silage, corn fodder 
and mixed hays are all valuable coarse fodders. Roots 
and tubers, to the extent of 10 to 15 pounds per day, may 
also be added to a beef ration. The amount of grain 
should range from 10 to 18 pounds per day with from 12 
to 18 pounds of coarse fodder. Occasionally heavy grain 
feeding is resorted to in the fattening of steers. When 
grains and milled products are cheap, this practice is 
often economical as it converts a cheap grain into a more 
valuable marketable product. Ordinarily the cost of pro- 
duction is greater with a heavy grain ration than with a 
light or medium one, and when more than 12 pounds of 
grain per day is fed, the additional amount is fed at a loss. 
When grains and feeding-stuffs are high in price, heavy 
grain feeding is not economical. In the production of 
beef, it should be the aim to secure the larger portion of 
growth, as well as the larger portion of the increase dur- 
ing the fattening, from high-grade coarse fodders, and 
supplement them with medium amounts of grain and 
milled products. The amount of grain that can be fed 
economically is regulated by its cost and the market price 
of the beef product. 



RATIONAL FEEDING OF ANIMALS 35 1 

476. Food Requirements of Dairy Cows. — For the 

production of milk, a more liberal supply of digestible 
protein is required than for beef production. From 0.4 
to 0.5 pound of digestible protein and from 7 to 7.5 
pounds of digestible carbohydrates are required for main- 
tenance. A ration should contain, in addition, 1.4 to 1.8 
pounds digestible protein and 4 to 6 pounds digestible 
carbohydrates, because milk cannot be produced econom- 
ically on too scant an amount of nutrients. According 
to the standard feeding tables, a ration for a cow giving 
a heavy yield of milk should contain 32 pounds dry mat- 
ter, 3.3 pounds digestible protein and 13 pounds carbohy- 
drates. For economic production of milk, this is a larger 
amount of protein than is necessary. Under average 
conditions, a ration containing about 27 pounds dry mat- 
ter, 1.8 to 2 pounds digestible protein, and 11 to 13 
pounds digestible carbohydrates will prove more econom- 
ical than one containing larger amounts of protein. In a 
milk ration, proteids must be furnished for the produc- 
tion of the albumin and casein in the milk. In 15 pounds 
of milk, there is about one-half pound of proteids, as 
albumin and casein, and this must be supplied from the 
food. For the production of milk, about as much more 
protein is necessary to supply the energy to produce the 
milk as is required for maintenance and the milk pro- 
teids. In an ordinary dairy ration, about one-fourth of 
the proteids is recovered in the milk as casein and 
albumin, one-fourth is indigestible, while one-half is 
present in the liquid waste and represents the protein re- 
quired for maintenance and the production of milk. The 



352 AGRICULTURAL CHEMISTRY 

amount of nutrients in a dairy ration should vary with 
the milk yield, as given in the table of feeding standards, 
but it is not necessary to adhere too closely to the figures. 

In the calculation of a dairy ration, it will be found 
that when ordinary foods are combined, the amount of 
ether extract or crude fat will exceed the figures given 
in the table. Provided the ration contains the requisite 
amount of digestible protein, and does not yield more 
than 32,000 calories, there is no objection to the crude 
fat amounting to 0.6 pound per day. It should not, 
however, in an average ration, exceed 0.75 pound. 

477. Selection of Foods for Dairy Cows. — The amount 
of grain which a dairy cow should receive varies from 7 
to 12 pounds per day. Occasionally 15 pounds can be 
fed economically, but, as a rule, medium grain rations of 
from 7 to 12 pounds produce milk and butter more eco- 
nomically than either light or heavy rations. As in beef- 
feeding, when more than 12 pounds per day of grain are 
fed, the additional amount is not used economically and 
is generally a loss. The coarse fodder in a dairy ration 
may vary from 18 to 50 pounds per day, according to the 
amount of water present in the foods. The ration should 
contain from 25 to 30 pounds of dry matter. When 
silage is fed, 20 to 40 pounds may be used because of the 
large amount of water present. In the feeding of roots, 
from 15 to 20 pounds per day will be found economical. 
In feeding dairy cows, it is not desirable to restrict the 
ration to one grain or milled product. Better results are 
secured from a mixture of two or three grains. No 
great differences have been observed in the milk-producing 



RATIONAL FEEDING OF ANIMALS 353 

value of the different grains and milled products. A 
pound of one grain in a mixed ration will produce about 
as good results as a pound of another grain. For exam- 
ple, wheat has been found to have practically the same 
feeding value as corn, oats, or barley. Common farm 
grains will give the same yield of milk and butter-fats as 
bran or shorts, and, on the whole, have a tendency to 
produce slightly better results. Oil meal in medium 
amounts in a ration, produces from 20 to 25 per cent, 
better results than bran. Oil meal, cottonseed meal, and 
gluten meal all have about the same general milk-pro- 
ducing value. 

Clover hay, corn silage, corn fodder, alfalfa and oat 
hay are among the most valuable coarse fodders for milk 
production, preference being usually given to clover hay 
when cut in early or full bloom. When silage is not 
fed, roots should always form a part of a dairy ration. 
Roots are valuable largely because of their palatability 
and the favorable influence which they exert upon diges- 
tion rather than for any large amount of nutrients. 

478. Food Requirements of Swine. — The nutrients 
required by swine vary with the stage of growth 
more than in the case of other animals. In the earlier 
stages of growth, particular attention should be given to 
furnishing a liberal supply of available protein and min- 
eral matter. A ration for a 100-pound animal should 
contain about 0.5 pound digestible protein and 2.5 pounds 
digestible carbohydrates while that for a 200- pound ani- 
mal should contain about 0.6 pound digestible protein 
and nearly 4 pounds digestible carbohydrates. For grow- 

23 



354 AGRICULTURAL CHEMISTRY 

ing pigs, a mixture of shorts and corn or shorts and 
barley with skim milk will be found preferable to any- 
single grain. Skim milk should not be used in greater 
amounts than 3 pounds for each pound of grain. Five 
pounds of skim milk will produce as much gain in weight 
as one pound of grain. For fattening pigs the grain mix- 
ture should contain more corn than shorts. Coarse 
ground barley is a valuable food and produces a good 
quality of pork. Peas may form about one-third of 
the grain mixture. For fattening purposes, foods with 
a large amount of digestible protein are not as essential 
as for growing animals because the excess of protein is 
used for the production of fat which can be produced 
from less expensive nutrients as carbohydrates. The 
food should not be too concentrated in character. Many 
of the grains are so highly digestible that there is present 
in the digestive tract only a limited amount of insoluble 
matter to dilute the waste products. This is particularly 
true of peas and corn. Charcoal and a small amount of 
corn- and cob-meal are found useful to correct such de- 
ficiencies. A small amount of some forage crop as chopped, 
steamed or soaked clover should be at the disposal of the 
animal. Wheat, barley and rye, if fed, should be coarsely 
ground, but in the case of corn, grinding is not so essen- 
tial. Bone-meal, dried blood, and meat scrap are valuable 
in a ration for pigs, particularly if corn is the principal 
grain used. Among the forage crops, rape, clover, alfalfa, 
sorghum and corn will be found most valuable for pork 
production. 

479. Food Requirements of Sheep. — In the case of 



RATIONAL FEEDING OF ANIMALS 355 

sheep, the standard rations, as given in the tables, can be 
adhered to more closely than for any other class of farm 
animals. This is because a large number 6f feeding trials 
and experiments have been made with sheep. More nutri- 
ents are required for sheep than for beef animals, and they 
are capable of making equally good returns from the food 
consumed. Experiments by Lawes and Gilbert have 
shown that during the process of fattening only a slight 
increase in nitrogen takes place ; the gain in weight is 
largely an increase in fat. During the growing period, 
a more liberal allowance of available protein is required 
than for fattening. Farm foods need but little reinforce- 
ment with mill and other products for the production of 
mutton. Henry, in ' 'Feeds and Feeding, ' ' states that about 
500 pounds of corn and 400 pounds of clover will produce 
100 pounds of gain in live weight of lambs, and he gives 
these figures for calculating the cost of production. The 
grinding of grains is not so necessary in sheep-feeding as 
in dairy feeding. Among the grains, corn, barley, wheat 
and oats have all been found valuable. Oil meal and 
other milled products are also suitable, provided their 
cost is not too high. Among the coarse fodders, clover 
hay, alfalfa, corn fodder and silage are particularly valu- 
able. Roots should also form a part of the ration. Vari- 
ety and palatability should be considered. 

480. Calculation of Balanced Rations. — In calculating 
a balanced ration, the food requirements of the animal, 
as given in the table of feeding standards, are first noted. 
A reasonable variety of coarse fodders, grains and roots 
is selected on the basis of cost, as explained in Section 



356 AGRICULTURAL CHEMISTRY 

483. A trial ration is then calculated, using the approxi- 
mate amounts of foods as given in the various sections 
relating to the food requirements of animals. The 
amounts of digestible nutrients in the foods selected are 
then calculated and the total amounts of the different 
nutrients determined. If these correspond with the 
figures given in the table, a reasonably well-balanced 
ration is secured. In case the nutrients are present in 
the right proportion but deficient in amounts, the weights 
of foods used are increased; if excessive, they are reduced. 
Should the ration be deficient in digestible protein, a 
small amount of some food containing a liberal supply of 
this nutrient may be added. Finally, when the require- 
ment as to amounts of nutrients is satisfied, the various 
other factors as bulk, suitable combinations, cost, and 
labor involved in preparation are to be considered. 

Example. — Calculate a ration for a dairy cow. The standard 
ration calls for 1.8 to 2 pounds digestible protein and from 10 to 
12.5 pounds digestible carbohydrates. It is necessary to combine 
the coarse fodders and grains so as to secure approximately these 
amounts of nutrients. A trial ration is calculated, composed of 10 
pounds each of clover-hay and corn fodder, 20 pounds of mangels, 
5 of bran and 3 of oats. The digestible nutrients in these materials, 
as given at the close of the chapter, are as follows : 
Digestible Nutrients. 

Carbohy- 
Protein. Fat. drates, etc. 

Wheat bran 12.9 3.4 40.1 

Mangel beets 1.1 0.1 5.4 

Clover hay 6.8 1.7 35.8 

Corn fodder 2.5 1.2 34.8 

Oats 9.2 4.2 47.3 

These figures are on the basis of 100 pounds. The 



RATIONAL FEEDING OF ANIMALS 357 

amounts of nutrients in one pound are found by moving 
the decimal point two places to the left. Multiplying 
the pounds of food by the per cent, of digestible nutri- 
ents, the pounds of digestible nutrients will be found to 
be as follows : 

Pounds of Digestible Nutrients. 

Pounds. Protein. Fat. Carbohydrates, etc. 

i o Clover hay 0.68 0.17 3.58 

10 Corn fodder 0.25 0.12 3.48 

20 Mangel-wurzels • 0.22 0.02 1.0S 

5 Bran 0.64 0.16 2.00 

3 Oats 0.28 0.13 1.42 

2.07 0.60 n.56 

Compared with the standard ration, it will be observed 
that the amounts of nutrients are approximately as given 
in the table, suggesting that as far as total nutrients are 
concerned, the ration is a reasonable one. The coarse 
fodder, grain, and roots are about in the proportions 
given in Section 477. As to the effects of the various 
foods, the bran, mangels, and clover hay might possibly 
prove somewhat laxative in character, and while the 
ration supplies all of the requisites, as dry matter and 
amount of nutrients, it would be necessary to note the 
effect upon the animal, before concluding that it was sat- 
isfactory in all respects. 

481. Nutritive Ratio. — The nutritive ratio is the ratio 
which exists between the digestible protein and the di- 
gestible non-nitrogenous compounds. A nutritive ratio 
of 1 to 6.7 means that for every 1 pound of crude pro- 
tein there are 6.7 pounds of digestible non-nitrogenous 
compounds. A wide nutritive ratio means a large 



358 AGRICULTURAL CHEMISTRY 

amount of non-nitrogenous to nitrogenous compounds, 
while a narrow nutritive ratio means a small amount of 
non-nitrogenous to nitrogenous compounds. 

To calculate the nutritive ratio, first determine the 
pounds of digestible protein in the food used, then the 
pounds of digestible carbohydrates, etc. Multiply the 
pounds of digestible ether extract by 2.2 because the fat 
produces 2.2 times as much heat, consequently is con- 
sidered 2.2 times more concentrated than the nitrogen- 
free extract compounds. Add the digestible fiber, nitro- 
gen-free extract and corrected ether extract and divide 
the sum by the digestible protein; the result is the nutri- 
tive ratio. The nutritive ratio of the ration given is 6.57 
(0.6 X 2.2 = 1.32) (1.32 + 11.56 = 12.88) (12.88-5-2.07 
= 6.02). 

482. Caloric Value of Rations. — The caloric value of 
a ration is determined by multiplying the pounds of 
digestible ether extract by the factor 4225 and adding this 
to the number secured by multiplying the sum of the di- 
gestible protein and carbohydrates by i860. As used in 
the calculation of rations, the carbohydrates include the 
nitrogen-free extract compounds and the digestible fiber. 
The term carbohydrates is used in the broad rather than 
the restricted sense. 

Problem 1. — Calculate a ration for a 1200-pound horse at light 
work. Use any foods desired. 

Problem 2. — Calculate a ration for a 1200-pound horse at heavy 
farm labor. 

Problem j. — Calculate a ration for a pig weighing 100 pounds. 
Problem 4. — Calculate a ration for a pig weighing 250 pounds. 



RATIONAL FEEDING OF ANIMALS 359 

Problem 5. — Calculate a ration for a dairy cow giving a full flow 
of milk. 

Problem 6. — Calculate a dairy ration for average milk yield. 
Problem 7. — Calculate a ration for a sheep weighing 100 pounds. 
Problem 8. — Calculate a ration for a growing steer weighing 500 
pounds. 

Problem 9. — Calculate a ration for a 1200-pound steer, fattening 
period. 

483. Comparative Cost and Value of Grains. — The 

market value of grains frequently differs from their actual 
food value. That is, a given sum of money if invested 
in one food article will often procure a larger amount of 
digestible protein and other nutrients than if invested in 
other foods. To illustrate : If corn is 50 cents and oats 
30 cents per bushel, $1.00 will purchase either 112 pounds 
of corn or 107 pounds of oats. Which is the cheaper and 
more valuable for feeding purposes ? The digestible 
nutrients in 100 pounds of corn and oats are as follows : 

Digestive nutrients. Pounds per hundred. 

Protein. Fat. Carbohydrates, etc. 

Corn 7.9 4.3 66.7 

Oats 9.2 4.2 47.3 

The amounts of digestible nutrients in 112 pounds of 
corn and 107 pounds of oats obtained by multiplying by 
the per cent, of digestible nutrients are : 

Carbohy- 
Pounds. Protein. Fat. drates. Calories. 

Corn 112 8.85 4.82 74.7 175,684 

Oats 107 9.84 4.50 50.6 131,407 

There is a difference of about 1 pound of digestible 
protein in favor of the oats and 24 pounds of digestible 
carbohydrates in favor of the corn; the dollar's worth of 



360 AGRICULTURAL CHEMISTRY 

corn would also contain about 44,000 more calories. At 
the prices given, corn rather than oats would more eco- 
nomically form the larger portion of a grain ration for 
work-horses, beef and dairy animals, and swine and sheep. 
For growing animals, however, a large amount of corn 
is not desirable. 

In deciding the comparative value of foods on the basis 
of their nutrient content, preference should usually be 
given to the protein, but when the difference in digestible 
protein is small, the preference should be given to the 
food containing the largest amount of available carbo- 
hydrates and number of calories. Comparisons between 
foods which are too unlike in character of nutrients can- 
not safely be made. It is not possible to assign an abso- 
lute value to any food upon the basis of any one or all 
of its digestible nutrients, because the comparative value 
of the different nutrients has not, as yet, been definitely 
ascertained. In the selection of foods, it will frequently 
be found that a given sum of money can best be invested 
in the purchase of two foods, one nitrogenous and the 
other non- nitrogenous, rather than in the purchase of 
one. The results of actual feeding standards should also 
be considered before definitely selecting foods. When 
both the available nutrients and the results of feeding ex- 
periments are considered, an accurate idea of the compara- 
tive cost and value of grains and milled products can be 
formed. 

Problem. — Complete the following table and calculate the avail- 
able nutrients and calories that can be procured for $1 when the 
various foods are at different prices. In making the calculations, 



RATIONAL FEEDING OF ANIMALS 



;6i 



use the prices of your local or home market. Select three of the 
cheapest and three of the most expensive foods from the list. 





Price 

per 

bushel 

or ton. 


Pounds 

for $1.00. 


Nutrients procurable for $1.00. 
Pounds digestible nutrients. 




Protein. 


Carbohy- 
drates. 


Ether 
extract. 


Calories. 
















Oats 








Wheat 

' ' bran .... 

' ' shorts . . 

Oil meal 

Linseed meal. . . 
Cottonseed meal 
Gluten meal 





484. Sanitary Conditions. — Satisfactory results in the 
feeding of animals can be secured only under the best 
sanitary conditions. When animals are kept in crowded 
quarters, deprived of pure air and sunlight, they fail to 
make the best use of the food consumed. Carbon dioxid 
thrown off from the lungs and ammonia produced from 
decaying manure form ammonium carbonate, a volatile 
and irritating compound. Sunlight is an important fac- 
tor for promoting animal growth. Experiments with 
growing calves have shown that under the same condi- 
tions of feed and management, animals reared with an 
abundance of sunlight make better gains in weight, and 
are more vigorous than those confined in dark quarters. 
The best results are obtained in the feeding of animals 



362 AGRICULTURAL CHEMISTRY 

when their surroundings are most sanitary. A large 
amount of available energy is often lost in warming up 
cold, wet bedding. Pure water, pure air, sunlight, clean 
quarters and dry bedding are as necessary to animals as is 
a well-balanced ration. 

Table of* Feeding Standards. 

Per 1000 lbs. live weight, daily. 
Digestible organic substances. 

Dry Car- 
sub- Pro- bohy- Nutri- 
stance. tein. drates. Fat. Total. tive 
Kind of animal. lbs. lbs. lbs. lbs. lbs. ration 

Fattening bovines 30 2.5 15. 0.5 18. 6.5 

Milk cows : 

Daily milk yield, 11 lbs • .. 25 1.6 10. 0.3 11. 9 6.7 

Daily milk yield, 16V2 lbs • 27 2. 11. 0.4 13.4 6. 

Daily milk yield, 22 lbs .. . 29 2.5 13. 0.5 16. 5.7 

Daily milk yield, 27V2 lbs . 32 3.3 13. 0.8 17. 1 4.5 

Sheep 22 1.3 11. 0.3 13.5 

Fattening sheep, first period 30 3. 15. 0.5 18.5 5.4 

Horses : 

Dight work 20 1.5 9.5 0.4 11. 4 7. 

Moderate work 24 2. 11. 0.6 13.6 6.2 

Severe work 26 2.5 13.3 0.8 16.6 6. 

Fattening swine : 

First period .. - 36 4.5 25. 0.7 30.2 5.9 

Second period 32 4. 24. 0.5 28.5 6.3 

Third period 25 2.7 18. 0.4 21. 1 7. 

Growing cattle (dairy breeds). 

Age in I<ive weight 
months, per head, lbs. 

2- 3 150 23 4. 13. 2. 21. 4.5 

3- 6 300 24 3. 12.8 1. 16.8 5.1 
6-12 500 27 2. 12.5 0.5 15. 6.8 

12-18 700 26 1.8 12.5 0.4 14.7 7.5 

18-24 900 26 1.5 12. 0.3 13.8 8.5 



RATIONAL FEEDING OF ANIMALS 



363 



Per 1000 lbs. live weight, daily. 
Digestible organic substances. 



Kind of animal 
Age in 
months. 


Eive weight 
per head, lbs. 


Dry 
sub- 
stance, 
lbs. 


Pro- 
tein. 

lbs. 


Car- 
bohy- 
drates, 
lbs. 


Fat. 

lbs. 


Total, 
lbs. 


Nutri 

tive 

ratio 1 


Beef breeds : 
















2- 3 




23 


4-2 


13. 




I9.2 


4-2 


3-6 




24 


3-5 


12.8 




17.8 


4-7 


6-12 




25 


2-5 


13.2 




16.4 


6. 


12-18 




24 


2. 


12.5 




15- 


6.8 


18-24 




24 


1.8 


12. 




14.2 


7.2 


Sheep : 

4-6 


65 


26 


4.4 


15-5 


0.9 


20.8 


4- 


8-1 1 


IOO 


24 


3-o 


14-3 


0.5 


17.8 


5-2 


Swine : 
















2- 3 


45 


44 


7.6 


28.0 


1.0 


35-7 


4.0 


3- 5 


no 


35 


5-o 


23.1 


0.8 


28.9 


5-o 


5-6 


150 


33 


4-3 


22.3 


0.6 


27.2 


5-5 




Digestible Nutrients 


in Fodders. 














Digestible 


nutrients in 


too lbs. 



Dry matter Carbohy- Ether 

Name of feed. in 100 lbs. Protein. drates. extract. 

Corn (all analyses) 89.1 7.9 66.7 4.3 

Dent corn 89.4 7.8 66.7 4.3 

Flint corn 88.7 8.0 66.2 4.3 

Sweet corn 91.2 8.8 63.7 7.0 

Corn cob 89.3 0.4 52.5 0.3 

Corn and cob meal 84.9 4.4 60.0 2.9 

Corn bran 90.9 7.4 59.8 4.6 

Gluten meal 91.8 25.8 43.3 n. o 

Germ meal 89.6 9.0 61.2 6.2 

Hominy chops 88.9 7.5 55.2 6.8 

Wheat 89.5 10.2 69.2 1.7 

Wheat bran S8.1 12.2 39.2 2.7 

Wheat bran (spring wheat) . 88.5 12.9 40.1 3.4 

Wheat bran (winter wheat). 87.7 12.3 37.1 2.6 



364 



AGRICULTURAL CHEMISTRY 



Dry matter 
Name of feed. in 100 lbs. 

Wheat shorts 88.2 

Wheat middlings 87.9 

Wheat screenings 88.4 

Rye 88.4 

Rye bran 88.4 

Rye shorts , . . . . 90.7 

Barley 89. 1 

Malt sprouts 89.8 

Brewers' grains (wet) 24.3 

Brewers' grains (dried) 91.8 

Oats 89.0 

Oat feed or shorts 92.3 

Oat hulls 90.6 

Buckwheat 87.4 

Buckwheat bran 89.5 

Flax seed 90.8 

Linseed meal (old process) . 90.8 

Linseed meal (new process) . 89.9 

Cottonseed meal 91.8 

Coarse Fodders. 

Fodder corn (green) 20.7 

Fodder corn (field-cured) . . . 57.8 

Corn stover (field-cured) 59.5 

Fresh Grass. 

Pasture grasses (mixed) 20.0 

Kentucky blue grass 34.9 

Timothy, different stages... 38.4 

Oat fodder. 37.8 

Peas and oats 16.0 

Hay. 

Timothy 86.8 

Redtop 91. 1 

Kentucky blue grass 78.8 



Digestible 


nutrients in 100 lbs. 


Protein. 


Carbohy- 
drates. 


Ether 
extract. 


12.2 


50.0 


3-8 


12.8 


53-o 


3-4 


9.8 


51.0 


2.2 


9-9 


67.6 


1.1 


n-5 


50.3 


2.0 


11.9 


45-1 


1.6 


8.7 


65.6 


1.6 


18.6 


37-i 


i-7 


3-9 


9-3 


1.4 


15-7 


36.3 


5-i 


9.2 


47-3 


4.2 


12-5 


46.9 


2.8 


i-3 


40.1 


0.6 


7-7 


49.2 


1.8 


7-4 


3°-4 


i-9 


20.6 


17.1 


29.0 


29-3 


3 2 -7 


7.0 


28.2 


40.1 


2.S 


37-2 


16.9 


12.2 


1.0 


11. 6 


O.4 


2.5 


34-6 


1.2 


i-7 


32.4 


O.7 


2.5 


10.2 


0.5 


3-o 


19.8 


O.8 


1.2 


19.1 


O.6 


2.6 


18.9 


I.O 


1.8 


7-1 


0.2 


2.8 


43-4 


1.4 


4.8 


46.9 


I.O 


4.8 


37-3 


2.0 



RATIONAL FEEDING OF ANIMALS 



365 



Digestible nutrients in 100 lbs. 



Dry matter 
Name of feed. in 100 lbs. 

Hay (continued). 

Hungarian grass 92.3 

Mixed grasses 87. 1 

Rowen (mixed) 83.4 

Oat hay 91. 1 

Straw. 

Wheat 90.4 

Oat 90.8 

Fresh Legumes. 

Red clover, diff. stages 29.2 

Alsike, bloom 25.2 

Crimson clover 19. 1 

Legume, Hay and Straw. 

Red clover, medium 84.7 

Red clover, mammoth 78.8 

Alsike clover 90.3 

Alfalfa 91.6 

Cow pea 89.3 

Silage. 

Corn 20.9 

Roots and Tubers. 

Potato 21. 1 

Sugar-beet 13.5 

Mangel beet 9. 1 

Rutabaga ■ 11. 4 

Carrot 11.4 

Miscellaneous. 

Pumpkin ( field ) 9.1 

Beet-pulp 10.2 

Cow's milk 12.8 

Skim milk (gravity) 9.6 

Skim milk (centrifugal) 9.4 

Buttermilk 9.9 

Whey 6.6 



Protein. 


Carbohy- 
drates. 


Ether 
extrac 


4-5 


5i-7 


1-3 


5-9 


40.9 


1.2 


7-9 


40.1 


1-5 


4-3 


46.4 


i-5 


0.4 


36.3 


0.4 


1.2 


33.6 


0.8 


2.9 


14.8 


0.7 


2.7 


!3-i 


0.6 


2.4 


13-9 


0.5 


6.8 


35-8 


i-7 


5-7 


32.0 


i-9 


8.4 


42.5 


1-5 


11. 


39-6 


1.2 


16. S 


38.6 


1.1 



0.9 



H-3 



0.7 



0.9 


16.3 


O.I 


I.I 


10.2 


O.I 


I.I 


5-4 


O.I 


1.0 


8.1 


0.2 


0.8 


7-8 


0.2 


1.0 


5-3 


°-3 


0.6 


7-3 




3-6 


4-9 


3-7 


3-i 


4-7 


0.8 


2.9 


5-2 


°-3 


3-9 


4.0 


1.1 


0.8 


4-7 


o-3 



CHAPTER XXXVII 
Composition of Animal Bodies 

485. Water and Dry Matter.— About half of the live 
weight of an animal is water. In fat animals, the pro- 
portion of water is less than in lean animals. The same 
general classes of organic compounds present in plants, 
as non-nitrogenous and nitrogenous, are also present in 
animal bodies ; the animal forms, however, are usually 
somewhat more complex than the plant forms. Animal 
bodies are characterized by containing a high per cent, of 
fat and proteid materials and a low per cent, of non- 
nitrogenous compounds other than fat. 

486. Mineral Matter. — The ash elements in the animal 
body are the same as those found in plants, and are 
nearly all furnished from vegetable sources. The body 
of an animal, live weight basis, contains from 2 to 4 per 
cent, of mineral matter, from a half to three-fourths of 
which is present in the bones, while the remainder is pres- 
ent both in solution in the various fluids, as the blood, 
chyle, etc., and deposited and combined with the solid 
and fleshy tissues of the body. Silicon in animal bodies 
is found mainly in the hair, wool and feathers. Sodium 
and chlorin, while unnecessary to plants, are absolutely 
necessary to animals. A thousand parts of blood yield 
about 4 parts of mineral matter, of which 1.2 are 
sodium chlorid. In the blood, salt is necessary as a sol- 
vent for the proteid s. 

The per cent, of ash in the carcasses of different ani- 



COMPOSITION OF ANIMAL BODIES 367 

mals varies, being greatest in the half-fat steer or ox, and 
least in the fat pig. In the process of fattening, the per- 
centage amount of ash is decreased. 

As in the case of the plant, the mineral matter of the 
animal body must be secured and assimilated in the early- 
stages of growth. Young pigs, or other young animals, 
fed exclusively on a food which like corn is poor in digesti- 
ble mineral matter, have bones which are weak and do 
not furnish a framework strong enough for the perfect 
development of the body in its last stages of growth. 
The same elements which are essential for plant growth 
are also essential for animal growth. 

487. Fat. — The per cent, of fat in the carcass of ani- 
mals ranges from 14 to 45 per cent, of the live weight. 
The carcasses of fattened steers of good quality consist 
of about one-third fat ; in moderately fat sheep there is 
somewhat more, while the 
largest amount is present in 
the body of the very fat pig, 
with the very fat sheep as a 
close competitor. " It is thus 
seen that animal food of re- 
puted high quality as sold by 
the butcher, and to which 
such a highly nitrogenous -houno- 
character is usually attributed, Fig ' 99-Composition of meat. 
will consist of fat to the extent of one-third to one-half 
of its total weight." (Lawes & Gilbert.) 

488. Nitrogenous Matter is present to the extent of 
10 to 18 per cent, in the live animal, being least in the very 




368 AGRICULTURAL CHEMISTRY 

fat pig and most in the half- fat ox. The offal parts, as 
the head, feet, tail, hair, wool, and horns, are quite rich 
in nitrogen but not so rich as the flesh. Beef-yielding 
animals, on the whole, contain rather more nitrogenous 
compounds than sheep, which in turn contain more than 
pigs. A large amount of the nitrogenous compounds of 
sheep and lambs is present in the wool (50 to 55 per 
cent). About 75 per cent, of the carcass of the sheep is 
consumed as food ; thus it will be seen that much less 
than half of the total nitrogen is really made use of as 
human food. Of the fattened pig, about three-fourths of 
the nitrogenous compounds are in the edible carcass. 
From 6 to 7 parts are in the bone, and about one-quarter 
is in the offal. About 8 per cent, of the nitrogenous 
compounds of the offal and a little over three-fourths of 
the total nitrogenous compounds of the pig are consumed 
as food. About two-thirds of the entire nitrogen of the 
calf and steer are in the butcher's carcass, and about 
12 per cent, is in the bones. From 5 to 7 per cent, of 
the nitrogen of the offal parts and about 60 per cent, of 
the total nitrogen of the steer are utilized as human food. 
In the table of relative composition of animal bodies, 
it will be noted that the mineral matter increases and de- 
creases with the nitrogenous matter. In the carcasses of 
all animals, it will be observed that the amount of fat al- 
ways exceeds the amount of nitrogenous matter, except 
in the case of the lean calf. In the bodies of animals in 
good condition, there is usually twice as much fat as dry 
protein. The following table is from the extensive work 
of Lawes and Gilbert. 



(COMPOSITION OF ANIMAI, BODIES 



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370 AGRICULTURAL CHEMISTRY 

489. Proteids of Meat.— Lean meat, fat-free, is a con- 
centrated nitrogenous material composed mainly of pro- 
teids but containing also small amounts of amides, albu- 
minoids and in some cases, alkaloidal bodies. The pro- 
teids are present mainly in insoluble forms ; a small 
amount, however, is soluble. The principal soluble meat 
proteids are albumin and syntonin. 

490. Albumin. — The formula C 72 H 112 N 18 S0 22 has been 
tentatively assigned to albumin. The amount of albu- 
min in meats ranges from 0.6 to 5 per cent. L,iebig gives 
as a mean 2.96 per cent. The lean meat of the pig as 
well as that of poultry contains a relatively large amount. 
Albumin is soluble in cold water, and is coagulated at a 
temperature of 157 to 163 F. and of 69 to 75 C. 
Dilute acids convert albumins into acid albuminates while 
alkalies produce alkali albuminates. The albuminates 
are proteids derived from albumins and other proteids 
by the action of acids or alkalies. 

491. flyosin. — Myosin is obtained from meat by extrac- 
tion with a weak solution of common salt. The myosin 
dissolves in the salt solution and is precipitated by heat 
and chemicals (see Experiments 60 and 61). Myosin is 
a globulin and in the living animal is present largely in 
soluble forms. 

492. Syntonin has the same general relationship to 
myosin as dextrin has to starch. Dextrin is derived 
from starch and syntonin is derived from myosin. Syn- 
tonin is an acid albuminate formed by the action of dilute 
acids. The amount of syntonin and myosin in meats is 



COMPOSITION OF ANIMAL BODIES 37 1 

small, never exceeding, according to Hoffman, 2 or 3 per 
cent. 

493. Hemoglobin. — When fresh meat is soaked in cold 
water, the solution becomes red in color on account of the 
hemoglobin which is extracted. Hemoglobin is a pro- 
teid which imparts the red color to the blood and is coag- 
ulated by heat at a temperature of 128 to 132 F. 
There is a sufficient amount of various salts in the 
blood to dissolve some of the fibrin proteids which are 
precipitated at a temperature of about 140 F. or 6o° C. 

494. Insoluble Proteids. — The larger portion of the 
nitrogenous material of the muscles is in the form of in- 
soluble muscular fiber. From 90 to 95 per cent, of the 
total nitrogenous matter of fat- free lean meat is present 
in soluble forms. In the grains, various insoluble pro- 
teids are found and in the different meats different kinds 
of insoluble proteids are present. Meats differ both as 
to the kinds and proportional amounts of the several 
proteids which they contain. 

495. Peptones. — When muscular fiber is acted upon 
by some ferments, peptones are produced. Only a small 
amount of peptones is present in meat. When meat is in 
cold storage to undergo the curing process before it is 
placed upon the market, the peptonizing process takes 
place to a slight exteut. If the process is too long con- 
tinued, ptomains, which are poisonous compounds, may 
develop. When meat of the best quality is produced, 
long curing is unnecessary. 

496. Keratin is an amide compound present in meat 



372 AGRICULTURAL CHEMISTRY 

juices in small amounts; ioo pounds of meat contain from 
0.07 to 0.32 of a pound. Like other amides, it pos- 
sesses less food value than protein. Keratin, sarkin 
and allied bodies are not coagulated by heat, but 
are gradually decomposed and give off characteristic 
odors when meat is being cooked. Keratin and sarkin 
are present in large amounts in beef extracts and although 
they possess no direct food value, they impart palatabil- 
ity and are mainly valuable on this account. 

497. Albuminoids, Gelatin. — When bone or muscular 
tissue is subjected to the action of boiling water, 
gelatin separates upon cooling and standing. Gelatin 
is quite different in chemical composition from albumin, 
muscular fiber and other proteids. Hoffmeister gives the 
formula as C ]02 H 151 O 39 . It contains no sulfur, while pro- 
teids contain from 1 to 2 per cent. Gelatin may prevent 
the rapid depletion of the protein of the body but cannot 
take its place as a nutrient. The approximate amounts 
of the nitrogenous compounds in lean meat are given in 
the following table from which it will be observed that 
only a small part is present in the meat juices. 
The Nitrogenous Compounds of Meat. 

Per cent. 

( Muscular fiber 12 to 18 

I Albumin 0.5 to 2.0 

'■ Proteids Myosin..... 0.4 to 0.6 

[ Syntonin 

2. Albuminoids Gelatin, etc 2.0 to 5.0 

f Keratin 0.07 to 0.34 

3. Amides <! Sarkin 0.01 to 0.03 

I Urea , 

4. Alkaloids (ptomaines) Occasionally traces. 



COMPOSITION OF ANIMAL BODIES 373 

498. Influence of Food upon the Composition of Ani- 
mal Bodies. — The nature of the food consumed has a 
noticeable effect upon the composition of the animal body. 
The food affects both the amount of meat produced and 
its composition. As a general rule, an unbalanced ration, 
particularly one with a large amount of non-nitrogenous 
compounds, produces flesh that is poor in circulatory pro- 
teids. But few systematic experiments have been made 
to study the influence of food upon the composition of 
animal bodies. 

499. Composition of the Human Body. — Halliburton 
states that the human body contains 58.5 per cent, water. 
The amount at different stages of life varies; in later life, 
the body contains less than during youth. Water is 
present in all parts of the body ; enamel contains 2 per 
cent., the gray matter of the brain 85 to 86 percent., 
bone about 50 per cent. , and muscle 75 per cent. The 
amount of fat varies between quite wide limits; normally, 
Moleschott states that it makes up from 4 to 5 per cent, 
of the weight of the body. Adipose tissue contains about 
85, marrow 96, and nerves 22 per cent. fat. Twenty- 
five percent, of the muscle is solid matter, of which 21 
per cent, is proteid and albuminoid material, and 4 per 
cent, is fat and nitrogenous extractive bodies. Mineral 
matter is present in small amounts combined with the 
muscular and other tissues and in solution in the various 
fluids and secretions. 



CHAPTER XXXVIII 
Rational Feeding of Men 

500. Similarity in the Principles of Human and Ani- 
mal Feeding. — The rational feeding of men is founded 
upon the same principles as the rational feeding of ani- 
mals. It is the object iu each case to supply the body 
with the right kinds and amounts of nutrients to meet 
all of its demands. It is not possible in either human or 
animal feeding to establish inflexible standards. 

501. Dietary Standards. — The standard rations which 
have been proposed by Atwater,. Voit and others call for 
about one- fourth of a pound each of fat and protein and 
a pound of carbohydrates in the ration of a man at aver- 
age muscular labor. Such a ration should yield about 
3,.20o calories. The actual amount of nutrients consumed 
by laborers does not always conform to this standard. 
For example, studies have shown that the negro laborer 
in the South often, by choice, consumes less than o. 1 
pound per day of protein, while a well-fed mechanic fre- 
quently consumes over 0.5 pound per day. While only 
tentative standards are proposed, experiments and 
dietary studies have shown that the best results are ob- 
tained in the feeding of men, as in the feeding of ani- 
mals, when the ration conforms within reasonable limits 
to the standard. By a dietary standard is meant the 
approximate amount of nutrients which the daily ration 
should contain. Such a standard as proposed by Atwater 
is as follows : 



Fat. 
lb. 


Carbohy- 
drates, 
lbs. 


Fuel Nutri- 
value. tive 
calories, ratio. 


0.20 


O.66 


2450 5-5 


0.22 


O.77 


2800 5.7 


O.28 


O.99 


352o 5-8 


0-33 


1. 10 


4060 5.6 


0.55 


i-43 


5700 6.9 



RATIONAL FEEDING OF MEN 375 

Protein, 
lb. 
Man with little physical exercise- 0.20 
Man with light muscular work . • 0.22 
Man with moderate muscular work 0.28 
Man with active muscular work. . 0.33 
Man with hard muscular work .. 0.39 

502. Amount of Foods Consumed per Day. — In com- 
bining foods to form human rations, there should be, as 
in animal rations, a variety of foods and no food article 
should be used in excessive amounts. The approximate 
amounts of food consumed per day by a man at average 
labor, are as follows : 

Range. Average. 

Ounces. Pound. 

Bread 6 to 14 0.50 

Butter 2 to 5 0.12 

Potatoes 8 to 16 0.75 

Cheese 1 to 4 0.12 

Beans 1 to 4 0.12 

Milk 8 to 32 

Sugar 2 to 5 0.20 

Meat 4 to 12 0.25 

Oatmeal 1 to 4 0.12 

In a balanced ration, it is the aim to obtain from all of 
the foods approximately 0.25 pound each of fat and pro- 
tein and a pound of carbohydrates. In case of severe 
work, larger amounts of nutrients, as indicated in the 
table, are necessary. The composition of human foods 
is given in the tables at the close of the chapter. 

In calculating the amounts of nutrients in fractions of 
a pound, the percentage composition of the food is mul- 
tiplied by the weight used, as in calculating animal ra- 
tions (see Section 480). 



376 AGRICULTURAL CHEMISTRY 

503. Calculating a Balanced Ration. — The various 
articles of food should be selected according to cost,, 
nutritive value,, purposes for which they are desired, 
amount and kind of work to be performed, and individual; 
preferences. When bread, butter,, milk, potatoes, sugar,, 
oatmeal, cornmeal, beef, ham and eggs, are to be com- 
bined to form a ration, such amounts are taken as will 
yield approximately 0.25 pound each of protein and fat, 
and a pound of carbohydrates. Such a combinations 
would be as follows : 

Nutrients. 

Amount Carbohy- 

per day. Protein. Fat. drates. 

Foods. Ounces. Pound. Pound. Pound. Calbries,- 

Ham ................. 4 0.04 0.09 ---• 480 

Eggs (2) - 0.03 0.02 .... 136 

Bread 8 0.05 0.01 ©; 28 650 

Butter 2 0.1 1 45° 

Potatoes 12 0.02 0.14 285 

Milk....... 16 0.04 0.04 0.05 325 

Sugar 2 0.12 20O' 

Oatmeal 2 0.02 o.or 0.09 230 

Beef (stew). -- - 4 0.04 0.05 . — 250 

Cornmeal 4 0.02 0.01 0.18 420 

0.26 0.34 0.86 3426 

This ration contains 0.26 pound protein, 0.34 pound 
fat, 0.86 pound carbohydrates and yields 3,426 calories. 
While it contains somewhat more fat and slightly less 
carbohydrates than the standard, it is sufficiently near 
the standard for all practical, purposes. Some vegetables 
and fruits should be added to the ration not so much 
with the object of increasing the nutrients as for the pur- 
pose of greater variety and palatability. In this ration,,. 



RATIONAL FEEDING OF MEN 



377 



the nutrients are secured from a variety of sources, the 
largest amount of protein coming from the bread. 
About one-third of the protein is supplied in the form of 
meat, one-fourth by the eggs and milk, while the balance 
is secured from the vegetable foods. Bread, potatoes, 
cornmeal and sugar supply most of the carbohydrates, 
the two ounces of sugar supplying nearly 14 per cent. 

In combining foods to form balanced rations, meats, 
beans, cheese, milk, bread and oatmeal supply protein, 
while pork, ham, bacon and other fat meats, butter, 
cheese and milk supply the fats. Carbohydrates are 
supplied more liberally from bread, rice, cornmeal, 
cereals, potatoes, sugar and vegetables. 

504. Comparative Cost and Value of Foods. — With 
human as with animal foods, the market price does not, 
as a rule, correspond with their nutritive value. When 
foods differ widely in cost, their relative values can be 




taz*; 



Fig. 100. — Comparative composition of milk, cheese, and butter. 

approximately determined by comparing the amounts of 



378 AGRICULTURAL CHEMISTRY 

nutrients which a given sum of money will procure in 
each case. The principle is the same as in the compari- 
son of cost and value of animal foods, Section 483. 

In making comparisons, preference cannot be given to 
any single nutrient. In general, however, foods which 
supply the largest amount of protein for a given sum of 
money are cheapest and most economical provided there 
is no great difference in the amounts of fat and carbohy- 
drates. When there is but little difference in protein 
content, preference should be given to foods yielding the 
largest number of calories. 

In order to calculate the nutrients which can be pro- 
cured for a given sum of money, first determine the 
pounds of food, then multiply the weight by the percent- 
age composition, using the figures in the tables. 

When round steak is 15 cents per pound and milk 5 
cents per quart, the amounts of nutrients which can be 
purchased for 1 5 cents are as follows : 

15 cents will buy 

Carbo- 
Protein. Fat. hydrates, 
lbs. lb. lb. lb. Calories. 

Round steak 1 0.18 0.12 870 

Milk 6 0.21 0.24 0.30 1950 

Three quarts of milk or six pounds contain 0.03 pound 
more protein and 0.12 pound more fat and yield over 
1,000 calories more than a pound of round steak costing 
the same. Milk at 5 cents per quart should be used lib- 
erally in the ration when steak is 15 cents or more per< 
pound. It does not follow that meat should be entirely 
excluded from the ration in favor of milk but the 



RATIONAL FEEDING OF MEN 379 

nutrients indicate that milk should be used in liberal 
amounts. 

Problem 1. — Calculate a balanced ration for a man at hard mus- 
cular labor and give the cost of the food articles required. 

Problem 2. — Calculate a ration for a man with little physical ex- 
ercise, giving cost of ration. 

Problem j. — Calculate the amounts of food and the nutrients re- 
quired for a family of seven for ten days, three of the family to be 
considered as consuming each 0.8 as much as an adult. Calculate 
the cost of the food. Then calculate, on the same basis, the prob- 
able amounts of food for one year with cost, adding 20 per cent, 
additional for fluctuations in market prices and foods not included 
in the ten-day list. 

Problem 4. — How do beef and mutton compare as to nutrients 
when they are the same price per pound ? 

Problem 5. — Calculate the comparative amounts of nutrients that 
can be procured when cheese is 16 cents and loin steak 20 cents 
per pound, and also when cheese is 20 cents and loin steak is 16 cents. 

Problem 6. — How do the nutrients in chicken at 12 cents per 
pound compare with those in round steak at 14 cents per pound? 

Problem 7. — How does flour at 2 cents per pound compare in 
nutritive value with a cereal breakfast food at 10 cents per pound, 
and having the same composition as whole wheat? 

505. Factors Influencing Digestibility. — The factors, 
discussed in Chapter XXXV, which influence the digesti- 
bility of animal foods also influence the digestibility of hu- 
man foods. The mechanical condition of the food and the 
method of preparation have a more pronounced effect in 
a human than in an animal ration. The term digesti- 
bility has, by some physiologists, been used to designate 
ease of digestion rather than completeness of the process, 
foods which are easily digested and require but little 



380 AGRICULTURAL CHEMISTRY 

work of the digestive tract being termed digestible, while 
those which require a larger amount of work are said to 
be indigestible. Some confusion has arisen from this use 
of the term digestible. For example, rice is frequently 
called a digestible food and cheese an indigestible food. 
Digestion experiments have shown that cheese is more 
completely digested than rice. A food which is easily- 
digested is not necessarily completely digested. 

Individuality influences the digestibility of foods to a 
marked extent. For example, digestion experiments 
have shown a difference of over 14 per cent, in diges- 
tibility of the protein in a mixed ration composed of 
bread, milk and beans. There is a greater difference 
between individuals as to the ease of digestion than as to 
the completeness. Since digestion is largely a biochemical 
process, its completeness is necessarily influenced by 
the activity of the cells in the digestive tract. The com- 
bining of foods influences digestibility. For example, 
milk in a ration exerts a favorable influence upon the di- 
gestibility of the other foods with which it is combined. 
This is because of the presence in milk of enzymes or 
soluble ferments. Experiments have shown that 12.5 
per cent, of the protein in a sterile food, as toast, is capa- 
ble of being digested by the soluble ferments of milk. 

The method of cooking and preparing foods also exerts 
an influence upon their digestibility. Cooking changes 
both the physical and chemical composition of foods. 
The cell walls of vegetables and cereals are broken and 
the starch granules ruptured, thus exposing them to 
more thorough action of the digestive fluids. Cooking 



RATIONAL FEEDING OF MEN 38 1 

influences the ease or rapidity of digestion to a greater 
extent than it does the completeness of the process. The 
carbohydrates are favorably influenced by the action of 
heat while, in some cases, prolonged heat may make the 
proteids less digestible. In pasteurized milk, for example, 
the proteids are slightly less digestible than in pure fresh 
milk, while in sterilized milk, the digestibility is notice- 
ably lessened. As in the case of animals, the mechanical 
condition of a food influences both the ease and the 
completeness of the process. With persons of sedentary 
habits, the best results are secured when a small amount 
of some coarsely granulated food is present. A large 
amount of such foods, however, is not suitable in the 
ration of a hard working man because of lack of avail- 
ability of the nutrients. 

506. Requisites of a Ration.— Reasonable combina- 
tions should be made in forming balanced rations. A 
number of foods which are slow of digestion or require 
much intestinal work should not be combined. Neither 
should a number of foods which are easily digested and 
leave but little indigestible residue. Two foods which 
are either laxative or costive should not be combined. 
After formulating a ration, it should be critically ex- 
amined to see if it satisfies the following conditions : ( 1 ) 
Foods economical and suitable to the work to be per- 
formed, (2) foods combined so as to secure balanced work 
of the digestive tract, (3) foods not too laxative or too cos- 
tive in effect, (4) requisite bulk, (5) sufficient amount of 
indigestible residue to dilute the waste products in the 
intestinal tract. 



382 AGRICULTURAL CHEMISTRY 

507. Dietary Studies. —A dietary study considers the 
cost and amount of nutrients consumed by individuals 
and families. It is an investigation in which men are 
used and human foods are studied instead of farm ani- 
mals and animal foods. Dietary studies have shown that 
frequently money is injudiciously spent in the purchase 
of high-priced foods which contains but a small amount 
of nutrients. In a dietary study, the amounts of nutri- 
ents in the foods exclusive of the refuse parts are deter- 
mined. From the weight of the foods, the nutrients 
contained are calculated using the tables, or they are 
determined by chemical analysis. 

The purchasing of food is frequently done without re- 
gard to nutritive value. Erroneous ideas as to the 
value of foods are often the cause of extravagance in 
their purchase and use. As for example, it has been 
claimed that the banana is as valuable as beef, and mush- 
rooms have been erroneously called vegetable beefsteak. 
Many other foods are assigned fictitious values. Too 
frequently, choice is made on the basis of palatability, but 
cost of nutrients and kind of work to be performed should 
be considered as well as palatability. Dietary studies of 
the United States Department of Agriculture have shown 
that lack of knowledge in regard to the value of foods 
has frequently resulted in whole families being underfed, 
not from necessity but from lack of judgment in the se- 
lection of foods. While it is not practicable or desirable 
to confine the ration to an absolute standard, dietary 
studies have shown that for long periods the best results 
are obtained when foods are combined so as to secure nu- 



RATIONAL FEEDING OF MEN 



383 



trients in approximately the amounts given. By means 
of a careful study of the dietary, it is possible to reduce 
the cost of food without impairing its nutritive value, 
and in many cases, as the cost is decreased, the nutritive 
value is increased. 

508. Chemical Changes in the Cooking of Foods. — The 
chemical changes which take place in cooking are brought 
about by the joint action of heat, water and ferments and 
occasionally by the use of chemicals. The various com- 
pounds of which foods are composed, namely, carbohy- 
drates, proteids and fats, are all susceptible to the action of 
these agencies and the chemical changes which they un- 
dergo are briefly discussed in Chapters XXIII and XXIV, 
treating of the composition of the nitrogenous and non- 
nitrogenous compounds. Some of the changes are phys- 
ical rather than chemical in character. All of the differ- 
ent nutrients of foods are influenced by the action of heat. 




Fig. 101.— Comparative composition of raw and baked beans. 

Starch, in the presence of water and heat, undergoes 
partial hydration, so that the material is in a condition 



384 AGRICULTURAL CHEMISTRY 

both chemically and mechanically to undergo readily in- 
version changes. In the cooking and preparation of foods, 
starch rarely undergoes more than the hydration 
change. In bread-making, for example, only a small 
portion of the original starch is converted into soluble 
forms. 

The action of heat upon cellulose and cellular tissue 
is mechanical rather than chemical. The mass is partially 
disintegrated and in the case of some of the cellulose, 
hydration takes place to a limited extent. Human foods, 
however, contain comparatively little of the cellulose 
group of compounds. The sugars are partially caromel- 
ized by heat, provided it is sufficiently intense, but in 
ordinary cooking operations, they undergo little or no 
chemical change unless associated with acids, alkalies 
or ferment bodies, in which case they may be converted 
into a number of chemical products. 

In the cooking of fruits, as the baking of apples, a por- 
tion of the levulose of the fruit-sugar is partially carbon- 
ized. In case the fruit is not fully matured, the pectose 
substances or jellies are converted into a more soluble 
condition by the action of heat. When heat is sufficiently 
intense, the essential or volatile oils are expelled. 

Fats, as a class, undergo slight oxidation changes by 
the action of heat. In the process of bread-making, for 
example, the fat extracted from the bread is different in 
character from that in the original flour. It is darker in 
color, and chemical tests show that it is slightly oxidized. 
Heat causes the proteids to undergo more complex 
changes than any other class of nutrients.- The soluble 



RATIONAL FEEDING OF MEN 385 

albumins are coagulated, the globulins also are coagulated, 
and if the heat is sufficiently intense, molecular changes 
take place, in which the elements composing the proteid 
molecule are rearranged in a different way forming, prac- 
tically, a new molecule with different chemical and phys- 
ical properties. Since the proteid compounds contain 
fatty acid radicals, carbohydrate-like bodies, amides and 
radicals of other compounds, a number of chemical 
changes may take place, varying with the degree of heat 
employed. 

The chemical changes which take place in the process 
of cooking influence, to a limited extent, the digestibility 
of the foods. As a rule, the total digestibility of the 
carbohydrate nutrients is changed but little by the action 
of heat. For example, experiments have shown that the 
carbohydrates in toast are no more completely digested 
than the carbohydrates in bread, but the action of heat 
in the preparation of toast produces chemical and phys- 
ical changes which render the nutrients more susceptible 
to the action of the digestive fluids, and while toast is no 
more completely digested than bread, it is more readily 
acted upon by the digestive fluids. Experiments show 
that prolonged heat has a tendency to decrease the di- 
gestibility of the proteid compounds as a class. In toast, 
the proteid nutrients are slightly less digestible than in 
bread. 

In general, it can be .said that cooking effects ease of 
digestion rather than completeness of the process, that 
the carbohydrates are practically as digestible before the 
action of heat as after and that the proteids are slightly 



386 AGRICULTURAL CHEMISTRY 

less digestible after the action of prolonged heat. Ex- 
periments in the feeding of animals have shown that when 
foods are cooked, the total digestibility of the nutrients 
is not increased, and in some cases, a smaller amount of 
nutrients was absorbed after cooking than before. This 
does not mean that the cooking of foods is undesirable 
because ease of digestion is equally as important as com- 
pleteness of digestion. Also cooking sterilizes the food, 
which is desirable. Many foods, if consumed uncooked, 
would be unwholesome because of the presence of ferment 
bodies or poisonous compounds as ptomains. When 
acted upon by heat, the ferment bodies are destroyed and 
the ptomain compounds decomposed. 

When salt, soda and other chemicals are used, chem- 
ical changes, to a limited extent, take place. Soda, for 
example, combines with the proteid compounds, forming 
alkali proteids and the acids form acid proteids. In 
cooking and preparing foods, many of the physical 
changes which take place precede and are necessary to the 
chemical changes. In the boiling of potatoes, for exam- 
ple, heat changes the physical character of the cells but 
does not alter the solubility of the starch. The albumin 
is coagulated and small amounts of the mineral com- 
pounds and other bodies are extracted. In the cooking 
of some of the cereals, as oatmeal, if the process is con- 
tinued for only a few minutes, the starch is not acted 
upon to any appreciable extent because of the relatively 
large amount of gelatinous proteids which protect the 
starch particles. If the cooking is continued for three 
or four hours, the material is disintegrated, the starch 



RATIONAL FEEDING OF MEN 



3*7 



cells are ruptured, and instead of masses of starch, small 
particles of disintegrated starch may be observed. This 
starch is partially hydrated. Oatmeal cooked in the two 
ways, for a few minutes, and for four hours, contains 
practically the same percentage amount of total starch. 
In the one case, however, the starch is in large masses, 
unruptured and unaltered, while in the other, the starch 
masses have been ruptured, the particles are in a finer 
state of division and are partially hydrated. Oatmeal 
which has been cooked for only a few minutes does not 
readily undergo digestion, but the four hours' cooking 
produces physical and intermediate chemical changes 
that cause the starch to 
yield readily to the action 
of the diastase ferment. 
In the cooking of 
meats, the heat liquefies 
a portion of the fat and 
oxidizes a portion of that 
which is exposed to the 
air, while the proteids 
undergo complex molec- 
ular changes. In the 
cooking and preparation 
of foods, it should be the 
object to bring about 
physical rather than 
chemical changes 




Tst: 



MJ 



Fig. 102. — Composition of bread. 

Cooking influences the ease rather 
than the completeness of digestion. 

509. Refuse and Waste Matters. — Nearly all foods 



388 AGRICULTURAL CHEMISTRY 

contain some refuse material which cannot be consumed 
as food. In average meat, as purchased in the market, 
from 7 to 56 per cent, is bone and trimmings. Round 
steak has least waste while shank has most. Tables 
showing the average amounts of refuse in meats are given 
at the close of the chapter. The amount of refuse and 
waste which a food contains is frequently large enough 
to make the nutrients of the edible portion quite expen- 
sive even in apparently cheap foods. In vegetables, the 
refuse ranges from 15 to 50 per cent. About 15 per 
cent, of the weight of potatoes is lost as parings ; of fresh 
peas, one- half of the weight is pods, and of squash, one- 
half the weight is rind and seeds. In calculating the 
nutrients of foods, the refuse and waste parts are to be 
considered, as there is nearly always a smaller percentage 
amount of nutrients in the food as purchased than in the 
edible portion. 

510. Loss of Nutrients in the Preparation of Foods. — 
In the cooking of vegetables, as potatoes, carrots and 
cabbage, some of the soluble nutrients, as albumin, sugar 
and mineral matter are extracted and lost in the water. 
In the case of potatoes, experiments have shown that 
over 57 per cent, of the total nitrogenous matter is ex- 
tracted and lost when the potatoes are cut in small pieces 
and soaked in cold water. When the cleaned, unpeeled 
potatoes were placed directly into hot water, the losses 
amounted to only 1 per cent. In the case of carrots and 
cabbage, the losses are large if the pieces are small and 
much water is used. The losses from meats incident to 
cooking need not necessarily be large provided mechani- 



. RATIONAL FEEDING OF MEN 389 

cal losses are avoided. In the boiling of meat, there is a 
decrease in weight of about 30 per cent, due largely to 
loss of water. About 5 per cent, of proteid matter is 
extracted, also 13 to 15 per cent, of fat and 51 per cent, 
of mineral matter. With small pieces of meat, the total 
loss of weight may be over 50 per cent. The amount 
of nutrients dissolved varies with the size of the 
pieces. From experiments made at the University of 
Illinois, there does not appear to be any great difference 
in the amount of nutrients extracted from meats by hot 
or cold water. If the broth is utilized for soup, the nu- 
trients extracted during cooking are not lost. 

511. Mineral Matter in a Ration. — In the calculation 
of human as well as animal rations, the mineral content 
of the food is not considered along with the other nutri- 
ents. This is not because the mineral nutrients are of 
insignificant value but because nearly all combinations of 
food contain sufficient, both in amount and variety, for 
food purposes. Phosphates, compounds of iron, potas- 
sium and magnesium are required only in comparatively 
small amounts. It is estimated that with a man at hard 
labor from 2 to 3.5 grams per day of phosphoric acid are 
eliminated through the kidneys. Since this includes all 
of the soluble mineral phosphates of the food, and not all 
of those are used for functional purposes, it is not neces- 
sary that the food should contain even 2 to 3.5 grams 
of available phosphates per day. A ration consisting en- 
tirely of white bread contains enough phosphates to sup- 
ply the body and establish a phosphate equilibrium. An 
average daily ration of mixed foods contains from 5 to 8 



390 AGRICULTURAL CHEMISTRY 

grams or more. Meats and nearly all animal foods con- 
tain about one per cent, of mineral matter of which about 
half is phosphoric acid. Milk and eggs contain phos- 
phates and mineral matter in liberal amounts. In a 
mixed ration of three or more food articles, there is al- 
ways enough phosphates and mineral matter for purposes 
of nutrition. A part of the excess of phosphates in a 
ration is eliminated through the kidneys. The feces also 
contain phosphoric acid. Inability of the organs to as- 
similate phosphates, due to malnutrition and lack of 
available forms of other nutrients, is more frequently a 
source of trouble than lack of phosphates in the food. 

It is estimated that in the ration of an adult, about 20 
grams per day of sodium chlorid are necessary. This- 
compound takes an important part in nutrition and is a 
normal constituent of all the fluids of the body. 

512. Digestibility of Foods.— The digestibility of 
foods is a subject which belongs for investigation alike 
to the chemist, the physiologist, and the bacteriologist. 
The physiologist considers the structure of the digestive 
tract and the functions of the various organs ; the chem- 
ist studies the chemical changes which occur while the 
food is undergoing digestion, the completeness of the 
digestion process, and the extent to which the nutrients- 
of the food are made available to the body ; the bacteri- 
ologist deals with the ferment bodies which assist in the 
process of digestion. 

513. Digestibility of Heats. — The nutrients of meats, 
particularly the fats and proteids r are more completely 



RATIONAL FEEDING OF MEN 39 1 

digested than the same classes of nutrients in vege- 
tables. From 93 to 95 per cent, or more of the pro- 
teids and fats from foods of animal origin are completely 
digested, while of vegetables not more than 85 per cent, 
of the proteids are completely digested except in the case 
of finely ground flour. Meats are concentrated foods as 
they furnish large amounts of nutrients in digestible forms. 
There is less difference in the completeness with which 
the various meats are digested than in the ease of diges- 
tion. Some meats, as pork, veal and mutton, which are 
called indigestible, are slow of digestion but are quite com- 
pletely digested. The nutrients of meats can, for all 
practical purposes, be considered entirely digestible. 

514. Digestibility of Vegetable Foods. — Vegetable 
foods are less completely digestible than animal foods. 
The larger the amount of cellulose or fiber, the less com- 
pletely digested is the food. Only a very small amount 
of the cellulose, even hydrated cellulose, of human 
foods is available to the body. In many vegetables 
the nutrients are enclosed in cellular tissue and 
thus, to a certain extent, are protected from the solvent 
action of the digestive fluids. The starches and carbo- 
hydrates of vegetables are more completely digested than 
the proteids. Frequently, 95 per cent, of the starch, 
while only 80 per cent, or less of the proteids, is digested. 
There is quite a wide range in the digestibility of the 
nutrients of vegetable foods. The nutrients of fruits are, 
as a rule, more completely digested than those from other 
vegetable sources, but fruits contain only comparatively 
small amounts of nutrients. 



392 AGRICULTURAL CHEMISTRY 

515. Relation of Food to Health. — Since the function 
of food is to supply the body with nourishment, the sub- 
jects of food and health are necessarily closely related. 
If too long continued, either an abnormal or too scant an 
amount of food affects the health. Not only is the 
amount important to health but also the quality of the 
food as nature of nutrients and sanitary condition. Many 
diseases result from malnutrition, while many others are 
caused by the use of foods in an unsanitary condition. 
Food may cause disease either on account of its unsani- 
tary condition or because of an excessive or deficient 
amount of nutrients, or because of an unbalanced con- 
dition of the nutrients. 



RATIONAL FEEDING OF MEN 



393 



Composition of Human Foods. 

(From Bulletins Nos. 28 and 34, Office of Experiment Stations.) 



Kind of food. 



Beef — Chuck ribs : 

Edible portion 

As purchased 

Loin : 

Edible portion 

As purchased 

Neck : 

Edible portion 

As purchased 

Ribs : 

Edible portion 

As purchased 

Round : 

Edible portion 

As purchased 

Rump : 

Edible portion 

As purchased 

Shank, fore : 

Edible portion 

As purchased 

Shank, hind : 

Edible portion 

As purchased 

Fore quarter : 

Edible portion 

As purchased 

Hind quarter : 

Edible portion 

As purchased 

Cooked, corn'd&can'd 
As purchased 

Dried and smoked : 
As purchased 



P4 D 



13.8 



I3.0 



27.6 



20.8 



7-7 



21.4 



36.9 



53-9 



19.4 



15.8 






57-3 
49-3 

60.5 
52.6 

63-4 
45-9 

55-4 
43-8 

65.8 
60.7 

56.7 

44-5 

67.9 
42.9 

67.8 
3i-3 

61.4 
49-5 

61.0 

51-3 

53-i 
50.8 



V o 

"Van 



42.7 
36.9 

39-5 

34-4 

36.6 
26.5 

44.6 
35-4 

34-2 
31.6 

43-3 
34-i 

32.1 
20.2 

32.2 
14.8 

38.6 

39-° 
32.9 

46.9 
49-2 



O u 

■V- V 



17.4 
15.0 

18.3 

15-9 

19.2 
13-9 

16.9 

13-4 

19.7 
18.1 

16.8 
13.2 

19.6 

12.3 

19.8 
9-i 

17-5 
14.1 

18.0 

15-2 

28.5 
31-8 



a o 

ft. u 



24.4 
21.1 

70. 2 
17.6 

16.5 
II.9 

26.8 

21.3 

13-5 
12.6 

25.6 
20.2 

11. 6 

7-3 

II-5 

5-3 

20.2 
16.3 

20.1 
17.0 

14.0 

6.8 



< u 



0.9 
0.8 



u c 

p 3 

ft. o 



1355 

1170 



1.0 1190 

0.9 1040 



0.9 
0.7 

0.9 
0.7 

1.0 

0.9 

0.9 

0.7 

0.9 
0.6 

0.9 
0.4 

0.9 
0.7 

0.9 
0.7 



1055 

760 

1445 
1 150 

935 

870 

1395 
1095 

855 
535 

855 
395 

1180 
950 

1 185 
1000 



4.4 1120 
845 



394 



AGRICULTURAL CHEMISTRY 



Composition of Human Foods — {Continued). 



Kind of food. 



Veal — Leg, whole : 

Edible portion 

As purchased 

Rump : 

Edible portion 

As purchased 

Fore quarter : 

Edible portion 

As purchased 

Hind quarter : 

Edible portion 

As purchased 

Lamb — Leg, hind : 

Edible portion 

As purchased 

Loin : 

Edible portion 

As purchased 

Neck : 

Edible portion 

As purchased 

Shoulder : 

Edible portion 

As purchased 

Mutton— Leg, hind : 

Edible portion 

As purchased 

Loin : 

Edible portion 

As purchased 

Neck : 

Edible portion 

As purchased ■> 

Shoulder : 

Edible portion 

As purchased 



(4 i> 



15-6 



30.2 



24-5 



20.7 



17-4 



14.8 



17-7 



20.3 



18.0 



15-3 



28.4 



21.7 



70.4 
59-4 

62.6 

43-7 

71.7 
54-2 

70.9 
56.2 

63-9 
52.9 

53-i 
45-3 

56.7 
46.7 

51.8 
41-3 

62.8 

5i-4 

50.1 
42.2 

58.2 
41.6 

61.9 

48.5 



29.6 
25.0 

37-4 
26.1 

28.3 
21.3 

29.1 

23.1 

36.1 
29.7 

46.9 
39-9 

43-3 
35-6 

48.2 
38.4 

37-2 
30.6 

49-9 
42.5 

41.8 
30.0 

38.1 
29.8 



O u 



20.1 
16.9 

20.1 
14.0 

19.4 

14.6 
19.8 

15-7 

18.5 
15.2 

17.6 
15.0 

17-5 
14.4 

17-5 
14.0 

18.2 
14.9 

15-9 
13.2 

16.3 

11. 7 

17-3 
! 3-5 



8.4 
7.2 

16.2 
"•3 

8.0 
6.0 

8-3 
6.6 

16.5 
13-6 

28.3 
24.1 

24.8 
20.4 

29.7 
23.6 

18.0 
14.9 

33-2 
28.6 

24-5 
17.6 

19.9 
15.6 



Hi 



I.I 
O.9 

I.I 

0.8 

O.9 

O.7 

I.O 
O.8 

I.I 
O.9 

1.0 

0.8 

1.0 

0.8 

1.0 

0.8 

1.0 

0.8 

0.8 

0.7 

1.0 

0.7 

0.9 
0.7 



3 rt 

v 

3 3 

to 2 



730 
620 



1055 
735 

700 
525 

720 

57o 

1040 
855 

1520 
1295 

L375 
1 130 

1580 
1255 

1 100 
9°5 

1695 
145° 

1335 
960 

1 160 
910 



RATIONAL FEEDING OF MEN 



395 



Composition of Human Foods— {Continued) . 



Kind of food. 



Mutton— (Contin'd). 

Fore quarter : 

Edible portion - 

As purchased 

Hind quarter : 

Edible portion 

As purchased 

Side, without tallow : 

Edible portion 

As purchased 

Pork — Flank : 

Edible portion 

As purchased 

Ham, smoked : 

Edible portion 

As purchased 

Shoulder, fresh : 

Edible portion 

As purchased 

Salt, clear fat : 
As purchased 

Salt, lean ends : 

Edible portion 

As purchased 

Bacon, smoked : 

Edible portion , 

As purchased 

Side : 

Edible portion 

As purchased 

Poultry — Chicken : 

Edible portion , 

As purchased • • •■ 

Turkey : 

Edible portion 

As purchased 



16.7 



19.2 



71.2 



14.4 



46.6 



8.0 



34-8 



22.7 



5i-7 
40.6 

54-8 
45-6 

53-i 
42.9 

59-0 
17.0 

40.7 
34-9 

57-5 
3°-4 

7-3 

19.9 
17.6 

18.2 
16.8 

29.4 
26.1 

74.2 
48.5 

55-5 
42.4 



Nutrients. 



48.3 
38-3 

45-2 
37-7 

46.9 
37-9 

41.0 
11. 8 

59-3 
50-7 

42.5 
23.0 

92.7 

80.1 
71.2 

81.8 
75-2 

70.6 
62.7 

25.8 
16.7 

44-5 
34-9 



15.0 
11.9 

16.2 

13-5 

15-4 
12.5 

17.8 
5-i 

15-5 
13-3 

15*6 
8-3 



7-3 
6-5 

10.0 
9.2 

8-5 
7-5 

22.8 
14.8 

20.6 
15-7 



- 1- 



32.4 

25-7 

28.2 
23-5 

3«-7 
24.7 

22.2 
6.4 

39-i 
33-4 

26.1 

14.3 

87.2 

67.1 
59-6 

67.2 
61.8 

61.7 
54-8 

1.8 
1.1 

22.9 

18.4 



. a 

< u 
0H 



V — 
3 Gt 

•30 



fo O 



O.9 

O.7 

0.8 

O.7 

0.7 
0.7 

1.0 

0.3 

4-7 
4.0 

0.8 
0.4 

3-7 

5-7 
5-i 

4.6 

4.2 

0.4 

0.4 

1.2 
0.8 

1.0 

0.8 



1645 
1305 

1490 
1245 

1580 
1275 

1265 
365 

1940 
1655 

1390 
760 

37i5 

2965 
2635 

3020 
2780 

2760 
2455 

500 
325 

1350 
1070 



396 



AGRICULTURAL CHEMISTRY 



Composition of Human Foods — ( Continued). 



Kind of food. 



Fish, fresh — Cod, dried: 

Edible portion 

As purchased 

Mackerel, entrails rem'd: 

Edible portion 

As purchased 

Salmon, Cal., sections: 

Edible portion 

As purchased 

Salmon trout, whole: 

Edible portion 

As purchased 

Trout, brook, whole: 

Edible portion 

As purchased 

Fish, pres'd, cod, salt: 

Edible portion 

As purchased 

Mackerel, salt: 

Edible portion 

As purchased 

Salmon, canned, as purc'd 
Sardines, can'd, as purc'd 

Shellfish, clams, round: 

Edible portion .... 

As purchased 

Oysters, "solids," aspur'd 

Dairy Products : 

Cheese — Cheddar 

Butter • 

*Milk 

*Cream 

Eggs : 

In shell 

Edible portion ...... 



29.9 



40.7 



10.3 



56.3 



24.9 



22.9 



67-5 



13-7 






82.6 
58.5 

73-4 
43-7 

63.6 
57-9 

69.1 
30.0 

77.8 
40.4 

53-6 
40.3 

42.2 
32-5 
64-5 
5 6 -4 

86.2 
28.0 
88.3 

33-O0 
13.00 
87.00 



63.1 

73-8 









17.4 

11.6 

26.6 
15-6 

36.4 
31.8 

3<>-9 
13-7 

22.2 
ii-5 

46.4 
34-8 

57-8 
44.6 
35-5 
43-6 

13-8 

4-5 

11.7 

67.00 
87.00 
13.00 



23.2 
26.2 



15.8 
10.6 

18.2 
11. 4 

17-5 
16. 1 

18.2 

7-7 

18.9 

9.8 

21.4 
16.0 

22.0 
17.0 
20.1 
25-3 

6.5 
2.1 
6.1 

28.00 
0.50 
3-5 
2-5 

12. 1 
14.9 



U, u 



0.4 
0.2 

7-i 

3-5 

17.9 
14.8 

11. 4 
5-4 

2.1 
1.1 

0.4 
0.4 

22.6 
17.4 
11.6 
12.7 

0.4 
0.1 
1.4 

35-oo 
85.00 
4.00 
20.0 

10.2 
10.5 



1.2 

0.8 

1-3 

0.7 

1.0 
0.9 

i-3 

0.6 

1.2 
0.6 

24.6 
18.4 

13.2 

10.2 

2.4 

5-6 

2.7 
0.9 
0.9 

4.0 

t-5 

0.7 

0.5 

0.9 

0.8 



5 as 
"SO 

> . 
— XI 

v a 
P 3 



310 
205 

640 
360 

1080 
9 2 5 

820 
985 

440 
230 

410 
315 

1360 
1050 



215 

65 

235 

1999 

3600 

323 



655 
721 



* Milk also contains 4.8 per cent, carbohydrates. 
rangtes frbin 10 to 30 per cent. 



The fat content Of cream 



RATIONAL FEEDING OF MEN 



397 



Composition of Human Foods — (Continued). 



Kind of food. 



Wheat flours, meals, etc 
*Roller process flour.... 

Spring wheat flour 

Winter wheat flour 

Buckwheat flour 

Cornmeal, bolted 

Oatmeal 

Rice 

Rice, boiled 

*White bread 

*Graham bread 

Crackers 

Sugar, granulated 

Sugar, maple 

Vegetables — Asparagus : 
As purchased 

Beans, dried. 
As purchased 

Beets : 

Edible portion 

As purchased 

Cabbage : 

Edible portion 

As purchased 

Carrots : 

Edible portion 

As purchased 

Parsnips : 

Edible portion 

As purchased 

Peas, dried : 
As purchased 

Peas, green : 

Edible portion 

As purchased 



150 



50.0 






11. 9 
11.6 

12.5 
14-3 
12.9 
7.2 
12.4 

52.7 

31.0 

32.2 

8.2 



94.0 

13.2 

87.6 
70.0 

9"-3 

76.8 

88.2 
7o.5 

79-9 
63-9 

10.8 

78.1 
39o 



■58 

O u 
PhPh 


V 


V 

'S.j 

V E 

it 

U 


a 

V. u 

< u 
<u 
Ph 


12.6 


O.8 


74-3 


O.4 


11. 8 


I.I 


75-0 


0.5 


10.4 


I.O 


75-6 


o-5 


6.1 


1.0 


77-2 


1.4 


8.9 
15.6 


2.2 

7-3 


75-i 
68.0 


0.9 
i-9 


7.8 


0.4 


79.0 


0.4 


5.0 


O.I 


41.9 


0.3 


9-9 


1.4 


57-i 


0.<5 


9-5 
10.7 


2.5 

9-9 


54-7 
68.8 
98.0 
82.8 


I.I 

2-4 


1.8 


0.2 


3-3 


O.7 


22.3 


1.8 


59-i 


3-6 


1.6 


O.I 


9.6 


I.I 


i-3 


O.I 


7-7 


O.9 


2.1 


0.4 


58 


1.4 


1.8 


0.3 


4-9 


1.2 


1.1 


0.4 


9.2 


I.I 


0.9 


0.3 


7-4 


O.9 


i-7 


0.6 


16.1 


i-7 


i-3 


0.5 


12.9 


1.4 


24.1 


I.I 


61.5 


2-5 


4-4 


0.5 


16.1 


0.9 


2.2 


0.3 


8.0 


0.5 



■ O-o 



— 13 
V S 
3 3 

to 2 



1650 
1660 
1640 
1590 
'655 
i860 
i6^o 

875 
1306 

1895 
1600 

i54o 

i°5 

159° 

210 
170 

165 
140 

210 

170 

355 
285 

1640 

400 
200 



* From Minnesota analyses. 



398 



AGRICULTURAL CHEMISTRY 



Composition of Human Foods — {Continued). 



Kind of food. 



Potatoes, raw : 
Edible portion .... 
As purchased 

Potatoes, sweet : 
Edible portion .... 
As purchased 

Squash : 
Edible portion .... 
As purchased 

Turnips : 

Edible portion 

As purchased 

Tomatoes : 
Edible portion .... 

Green corn 

Cucumber 

Spinach 

Sauer kraut 



*l 



15.0 



150 
50.0 
30.0 



ii c 



78.9 
67.I 

69-3 
58.9 

86.5 

43-3 

88.9 
62.2 

96.0 

81.3 
96.0 
92.4 
86.3 



*£ 



2.1 

1.8 

1.8 
i-5 

1.6 
0.8 

i-4 
1.0 

0.8 
2.8 
0.8 
2.1 
1-5 



O.I 

0.1 

0.7 
0.6 

0.6 
0.3 

0.2 

O.I 

0.4 

I.I 
0.2 

o-5 
0.8 



18.0 

15.3 

27.1 
23.1 

10.4 
5-2 

8.7 
6.1 

2-5 
14. 1 
2-5 
3-i 
4-4 



0.9 
0.7 

1.1 
0.9 

0.9 

0.4 

0.8 
0.6 

0.3 
0.7 

0.5 
i-9 
7.0 



INDEX 



Acid, citric 207 

hydrochloric 80-82 

malic 206 

oxalic 206 

phosphoric 94 

salts 75 

sulfuric 99 

tannic 207 

tartaric 206 

Acids 37) 72 

basicity of 76 

fatty 199, 201 

naming of 74 

organic 205 

Aerobic ferments 319 

Air 66-71 

a mechanical mixture 66 

ammonium compounds of .. .68 

as plant food 71 

carbon dioxid of 66, 68 

impurities in 70 

moisture in 69 

Albumin in meat 370 

Albumins 218 

Albuminates 220 

Albuminoids 226-228 

food value of ..... 227 

Alfalfa 267 

Aliphatic series 114 

Alkaloids 231 

Allotropism 48 

Aluminum 145 

in plants 1 68 

Alums 146 

Amides 228-231 

food value 230 

occurrence in animals- -229 

plants • . .229 

Ammonia 88 



Ammonia, properties of ... 89 

uses of 90 

Ammonium compounds in air- • -68 

Anaerobic ferments 319 

Anhydrids 91 

Animal bodies, composition of- 

366-369 

fat in 367 

mineral matter 

in 366 

nitrogenous mat- 
ter of 368 

Animal life, chemical change 2 

Apatite 93 

Apparatus, names of 19-21 

Apples 134 

Argon 70 

Aromatic series 114 

Arsenic, occurrence 15 2 

poisoning 153 

Ash determination 160 

Ash elements, essential 162 

of animal bodies 366 

of plants 159-174 

composition of 173 

Atomic weight 13 

table of 11 

Atoms • 4 

Bacteria, disease- producing . . . . 323 

Balanced rations 344 

calculation of -355 

Barley 297, 302 

grading of 301 

Bases 72 

naming of 74 

Beans 299 

Beef production, foods for -348-351 
Benzine 113 



400 



INDEX 



Bessemer process 142 

Blast-furnace 141 

Bleaching powder 136 

Bordeaux mixture 149 

Brick 147 

Bromus Inermis 265 

Buckwheat 298 

Burette 77 

Calcium 134 

carbonate 134 

chlorid 136 

compounds 134-139 

hydroxid 135 

hypochlorite 136 

in plants 168 

oxid 135 

phosphate 136 

sulfate 136 

Caloric value of rations 358 

Calorie 184, 327 

Calorimeter 327-331 

Caudle, chemistry of 52-54 

power 112 

Capillarity of plant tissue 241 

Carbids 115 

Carbohydrates 176-196 

digestibility of.. 333 

Carbon 46-55 

a reducing agent 48 

compounds 54 

a decolorizer 52 

deodorizer 52 

dioxid 107 

in air 66-68 

test for 135 

disulfid 114 

monoxid 108 

occurrence 46 

oxids of 107 

preparation of 46 

properties of 47 

role in plant and animal 

We 54-55 

Carbonates 107 



Carrots 313 

Cellulose 177-181 

chemical properties of 178 

food value of 179 

function of 178 

physical properties of . 177 

Chemical affinity 5 

analysis 6 

changes 2 

properties denned ..9-10 

Chemistry 2 

Chlorids 85 

Chlorin 82 

family 84 

preparation 83 

properties 84 

Chlorophyl 242-246 

function of 245 

production 243 

Clay 105 

Cleaning apparatus 28-29 

Climate and plant growth ..... 260 

Clover, composition of 250 

early and late cut 249 

hay 266, 271 

rapidity of growth 248 

Coal 48 

Combination of elements. 12, 16, 17 

Combustion 49 

products of 53 

spontaneous 51 

Composition of matter 1-7 

Compounds 5 

Cooking of foods, changes during 

carbohydrates 384 

fats 385 

proteids 385 

losses during 388 

Copper 148 

compounds 148-149 

sulfate J48 

Corks, perforation of 22 

Corn (see maize). 

flour 294 

fodder. 268 



INDEX 



4OI 



Cottonseed cake and meal 308 

Creosote 113 

Crop growth and soils 258 

Crops, improvement of 262 

Crude fiber 1 79 

protein 224 

Crystallization, water of 58 

Dairy cows, food for 352 

requirements of 351 

Definite proportion, law of 15 

Dextrin 186 

Dextrose 190 

chemical and physical 

properties of 191 

Dialysis 104 

Dietary standards 374 

studies = 382 

Digestible nutiients 341 

in fodders and 
grains... 363-365 
Digestion, a bio-chemical pro- 
cess 325 

chemistry of . . -325-344 

coefficients 339 

not con- 
stant-... 339 

experiments 325 

factors influencing .334 
Digestibility, factors influencing 

379-381 

influence of cook- 
ing upon .... 338, 385 

Disease, air 70 

and water supply 59-60 

Double salts 75 

Dry matter 157 

Elastin 227 

Elements and compounds, prop- 
erties 8-18 

classification of 72 

combination of .12, 16, 17 

cycle of 119 

Energy, available, of foods • . . .331 



Energy, net, of foods 332 

Epsom salt 138 

Equations 120-126 

for classroom . . . 124-126 

Essential oils 208-21 1 

food value 210 

synthetic produc- 
tion of 210 

Ether extract 203-204 

Fat in animal bodies 367 

Fats 197-205 

amounts of, in foods 203 

chemical properties 198 

digestion of 334 

food value of 201 

formation in plants 197 

heat from 201 

physical properties 1 98 

Feeding of animals 344-356 

and sanitary conditions 361 

standards 362 

stuffs, inspection of . . .310 

Feldspar 1 05 

Fermentation 31S-324 

conditions neces- 
sary for 320 

Ferments, aerobic 319 

anaerobic 319 

and bread-making ..321 
in butter- and cheese- 
making 321 

disease-producing. ..323 

and food digestion .-322 

preservation 322 

in seeds 320 

soils 320 

insoluble 318 

soluble 318 

Fertilizers, phosphate 94 

Fiber, crude 1 79 

Filter-paper, folding of 26 

Flame, structure of 52 

Flax, rapidity of growth 251 

Flaxseed, grading of 301 



4-02 



INDEX 



Fodders, composition of. -.263-272 

cutting of 260 

Foods, caloric value of 327 

combination and digesti- 
bility of 336 

cost and value of 359 

factors influencing di- 
gestibility ... 379-381 

influence of cooking up- 
on digestibility 338 

mechanical condition of, 

and digestion • • 335 

palatability of 337 

refuse and waste matters 

of 387 

Food, relation of, to health 392 

requirements of animals .345 
supply and stage of 

growth 346 

Formula 12 

Formulas, structural 186 

Fruits 314-316 

dried 316 

food value 317 

Fuels 115 

Galvanized iron 150 

Gasoline, use of 1 10 

Gelatin 227, 372 

Germination of seeds 237-239 

conditions nec- 
essary for • . 239 

Glass • 138 

tubing, bending. • • 22 

cutting • 21 

Gliadin 275 

Globulins 219 

Glucose, test for 149 

Gluten • • 277 

meal 309 

Glutenin 275 

Grains, composition of 302 

cost and value of 359 

grading of 299 

Grapes 315 



Grass, pasture 268 

Gypsum 1 36 

Helium -70 

Hemoglobin 371 

Horses, foods for 348 

food requirements of- • .347 
Human and animal feeding com- 
pared 374 

body, composition of. --373 

food problems 379 

foods, composition of . . 

393 -39 s 

cost and value of 377 

rations • 376 

calculation of • • -376 

requisites of 381 

Hydrated cellulose 178 

Hydrocarbons 109 

Hydrochloric acid 80-82 

preparation ... 80 
properties ... .82 

Hydrogen 37-4 1 

importance 41 

occurrence 37 

preparation 37-3S 

properties 39 

peroxid 70 

sulfid • 102 

Hydroxyl 72, 74 

Illuminating gas ...m 

Indestructibility of matter 3 

Insecticides. 152 

Insoluble proteids 222 

Invert sugars . • 189 

Iron 140 

compounds 140-144 

Iron, galvanized 150 

in plants 168 

ores, reduction 140 

rusting of ■ • • 144 

wrought 142 

Keratin 371 



INDEX 



403 



Kerosene oil, testing of no 

Laboratory manipulation .... 19-30 
practice, importance. 19 

Lactose 1S9 

Law of definite proportion 15 

multiple proportion 91 

Lead 150 

carbonates 151 

compounds T50, 151 

oxids 150 

uses of 151 

Lecithin 234 

Lemons 314 

Levulose 192 

Ligno-cellulose 178 

Lime kiln 134 

Lime, slaking of 137 

Limestone 134 

Linseed meal 307 

Magnesium, occurrence 138 

in plants 167 

salts 138 

Maintenance ration 344 

Maize as food 294 

as forage 252 

composition of 252-256 

kernel 289 

grading of 293 

husk 255 

leaves 254 

nitrogenous and non- 
nitrogenous 291 

products 294 

proteids of 290 

roots 252 

stalk 253 

structure of kernel 289 

varieties of 293 

Malt sprouts 309 

Maltose 1 89 

Mangels 313 

Marsh gas 109 

Matter, indestructibility of 3 



Measuring liquids 24 

Meats, albumin of 370 

albuminoids of 372 

composition of 393-396 

digestibility of 390 

proteids of 370 

Mechanical mixtures 6 

Mercury 153 

compounds 153 

Metric equivalents 23 

Mica 105 

Milk solids 158 

sugar 189 

Mill and by-products 303-311 

Millet 299 

Mineral food, assimilation of, by 

plants 247 

matter of crops. . . 159-174 

oils 112 

in a ration 389 

Minium 151 

Molecules 3 

Molecular weights n-14 

Mortar 137 

Mucin 227 

Multiple proportion, law of 91 

Myosin 370 

Naming of acids 74 

bases 74 

salts 75, 76 

Neutralization 72, 76 

Nitrates 86 

Nitric acid 86-88 

importance 88 

preparation 86 

properties 88 

Nitrogen 42-46 

assimilation of, by plants, 

247 

compounds, importance 

. of - \ 45, 92 

determination of 225 

Nitrogen-free extract. 196 

Nitrogen, occurrence 42 



404 



INDEX 



Nitrogen, oxids of 90 

preparation 42-43 

properties 44 

role in plant and ani- 
mal life 45 

Nitrogenous compounds. . .214-235 
matter, animal bodies 

363 

Non-nitrogenous compounds, food 

value 213 

Non-nitrogenous compounds, gen- 
eral relationship 212 

Note-book, laboratory 27 

Nuclein 226 

Nutrients, digestible, of foods.. 341 

Nutrition 325-366 

Nutritive ratio 357 

Oat feed 308 

hay 265 

Oats, composition of 296 

as food 297 

grading of 300 

structure of kernel 296 

Olein 200 

Olives 316 

Oranges 314 

Organic compounds in plants.. 117 

matter 1 75 

decay of 118 

production of... 245 

Osmosis 241 

Oxidation 35 

Oxids 34 

Oxygen 31-37 

importance 35 

occurrence 31 

preparation 31 

properties 34 

Ozone 70 

Palmitin 199 

Paris green 153 

Parsnips 313 

Pectin bodies 196 



Pentosans • • 195 

Peptic ferments 322, 333 

Peptones 221 

Petroleum 109 

Phosphates 94 

fertilizers 94 

in human foods 389 

Phosphoric acid 94 

Phosphorus 93 

compounds 95 

importance 95 

oxids 93 

in plants 169 

properties 93 

Physical change 2 

properties defined . ..8-18 

Physics 2 

Pigs (see swine). 

Plant ash 155-174 

growth 235-246 

juices, movement of. ... . 240 

life, chemical change 2 

physical change 2 

Plaster of Paris 1 36 

Plumbing 29 

Polariscope 193 

Porcelain 147 

Potassium • • 127 

carbonate 129 

chlorate 129 

compounds 127-130 

hydroxid 127 

nitrate 128 

in plants 164 

sulfate 1 29 

Potatoes 312 

Pottery 147 

Prairie hay 265 

Properties, chemical 9-10 

of elements and com- 
pounds 8-18 

physical 8-9 

Proportion, law of definite 15 

Protein, crude 224 

Proteids 215 



INDEX 



405 



Proteids, amount in plants 224 

chemical properties -.217 

classification 218 

digestibility of 333 

food value 223 

insoluble 222 

of meat 370 

physical properties. . .216 

of wheat 274 

Proteoses 221 

Protoplasm 243 



Quartz 



103 



Radicals 73 

naming of 74 

Rape 267 

Rational feeding of animals . 344-366 
men .... 374-398 

Rations, balanced 344 

caloric value of 358 

maintenance 344 

standard 345 

Reactions 120-126 

illustrated 121, 122 

impossible 123 

Reagent bottles, handling of . ... 25 

Reduction 48 

Rice 298 

Roots 312, 313 

Rye 298, 302 

grading of 300 

Salts 75 

acid 75 

double 75 

naming of 75, 76 

Sand culture 164 

Sanitarv conditions and feeding 

" 36i 

Saponification 200 

Seeds 235-239 

ash of 235 

and crop growth 257 

nitrogenous compounds of 236 



Sheep, food requirements of . • .354 

Silage 269 

Silica 103 

Silicates 105 

Silicic acid 103 

Silicon 103 

compounds, importance 

of 105 

Silo, losses in 270 

Sodium 1 29 

carbonate 131 

chlorid 130 

hydroxid 132 

nitrate 131 

phosphate 132 

in plants 168 

salts 130-133 

Soils 105 

Spontaneous combustion 51 

Starch 181-186 

chemical properties 181 

food value 184 

function 183 

physical properties 182 

in seeds 237 

Stearin 199 

Steel 142 

Steer feeding 348-35 1 

Stover 268 

Straw 263 

Strawberries 315 

Sucrose iSS 

chemical properties 188 

physical properties 188 

Sugar 187-195 

beets 194 

Sulfates 101 

Sulfids 101 

Sulfur 97 

dioxid 98 

preparation 97 

properties 97 

uses 98 

in plants 170 

Sulfuric acid 99 



406 



INDEX 



Sulfuric acid properties ioo 

Swine, food requirements of 353 

Symbols 10 

Syntonin 370 

Timothy hay 264, 274 

Tin 150 

salts 150 

Tubing, glass, bending 22 

cutting 21 

Turpentine • 113 

Typhoid bacillus 59 

Trypsin 333 

Valence • 15 

table of 11 

Vegetable foods 397-398 

digestibility of. 391 
Ventilation of rooms 67-69 

Water 56-65 

borne diseases 59 

contamination of 61, 62 

culture 163 

of crystallization 58 

distillation of 57 

electrolysis 56 

niters 63, 64 

mineral matter of 61 

natural 59 

organic matter in 60 

oven 155 

physical properties 57 

in plants 155, 157 

purification of 64, 65 



Waxes 201 

Weighing 23, 160 

Weights, atomic 11, 13 

molecular 14 

Wheat 273-388 

American and foreign . . . 288 

as animal food 286 

as human food 287 

bran 304 

bread-making properties 

of 277 

by-products 303 

composition of varieties • 285 

flour, grades of 303 

germ 306 

gluten of 277 

grading of 283 

influence of climate upon 281 
fertilizers upon 

279 

middlings 305 

nitrogen content of, and 

flour 278 

proteids of 274 

rapidity of growth 247 

screenings 307 

shorts 306 

storage of 282 

structure of kernel 273 

unsound ■ 284 

variations in composition 279 
White lead 151 

Zeolites 105 

Zinc compounds 149 

occurrence 149 



CORRECTIONS 

Page 23, in last line, read "S0 4 ," not "S0 2 ." 
Page 94, line 21, read " H 4 P 2 7 ," not " H 2 P 2 7 .' 
Page 125, Equation 40, read " 3KOH." 
Page 132, line 18, read "Na 2 HP0 4 ." 



A PRACTICAL BOOK FOR DAIRYMEN, 



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A GOOD BOOK FOR THE FARMER. 



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